Fecal Microbial Transplant Capsules Are Safe in Hepatic Encephalopathy: A Phase 1, Randomized, Placebo-Controlled Trial

Unraveling the Microbiome-Human Body Axis: A Comprehensive Examination of Therapeutic Strategies, Interactions and Implications

This review scrutinizes the intricate interplay between the microbiome and the human body, exploring its multifaceted dimensions and far-reaching implications. The human microbiome, comprising diverse microbial communities inhabiting various anatomical niches, is increasingly recognized as a critical determinant of human health and disease. Through an extensive examination of current research, this review elucidates the dynamic interactions between the microbiome and host physiology across multiple organ systems. Key topics include the establishment and maintenance of microbiota diversity, the influence of host factors on microbial composition, and the bidirectional communication pathways between microbiota and host cells. Furthermore, we delve into the functional implications of microbiome dysbiosis in disease states, emphasizing its role in shaping immune responses, metabolic processes, and neurological functions. Additionally, this review discusses emerging therapeutic strategies aimed at modulating the microbiome to restore host-microbe homeostasis and promote health. Microbiota fecal transplantation represents a groundbreaking therapeutic approach in the management of dysbiosis-related diseases, offering a promising avenue for restoring microbial balance within the gut ecosystem. This innovative therapy involves the transfer of fecal microbiota from a healthy donor to an individual suffering from dysbiosis, aiming to replenish beneficial microbial populations and mitigate pathological imbalances. By synthesizing findings from diverse fields, this review offers valuable insights into the complex relationship between the microbiome and the human body, highlighting avenues for future research and clinical interventions.

The Progression of Microbiome Therapeutics for the Management of Gastrointestinal Diseases and Beyond

There has been an increased ability to investigate human microbiota through next-generation sequencing and functional assessment. This advancement has rapidly expanded our ability to study and manipulate the gastrointestinal microbiome to mitigate disease. Fecal microbiota transplantation, a therapy that broadly transfers the entire intestinal ecosystem, has been explored as a potential therapeutic in a variety of gastrointestinal, hepatic, and extraintestinal conditions. The field, however, continues to evolve, with a movement toward precision microbiome therapeutics individualizing care for various disorders. This review will describe the use of fecal microbiota transplantation, microbiota restoration, and precision microbiome therapeutics focusing on gastrointestinal and hepatic diseases.

Recent advances in the prevention and treatment of decompensated cirrhosis and acute-on-chronic liver failure (ACLF) and the role of biomarkers

The progression of cirrhosis with clinically significant portal hypertension towards decompensated cirrhosis remains clinically challenging and the evolution towards acute-on-chronic liver failure (ACLF), with one or more extrahepatic organ failures, is associated with very high mortality. In the last decade, significant progress has been made in the understanding of the mechanisms leading to decompensation and ACLF. As portal hypertension advances, bacterial translocation across an impaired gut barrier culminates in endotoxaemia, systemic inflammation and cirrhosis-associated immune dysfunction (CAID). Gut-derived systemic inflammation and CAID have become the logical targets for innovative therapies that prevent hepatic decompensation episodes and the progression to ACLF.Furthermore, classification of disease and biomarker discovery to personalise care have advanced in the field. This review discusses progress in biomarker discovery and personalisation of treatment in decompensated cirrhosis and ACLF.

Minimal Hepatic Encephalopathy

Minimal hepatic encephalopathy (MHE) is a pervasive frequent complication of cirrhosis of any etiology. The diagnosis of MHE is difficult as the standard neurologic examination is essentially within normal limits. None of the symptoms and signs of overt HE is present in a patient with MHE, such as confusion, disorientation, or asterixis. Progress has been made in diagnostic tools for detection of attention and cognitive deficits at the point of care of MHE. The development of MHE significantly impacts quality of life and activities of daily life in affected patients including driving motor vehicles and machine operation.

Pathophysiology of Hepatic Encephalopathy: A Framework for Clinicians

Hepatic encephalopathy (HE) is a neuropsychiatric syndrome that is observed primarily in patients with liver disease. The pathophysiology is complex and involves many factors including ammonia toxicity, dysregulation of central nervous system activity, and excess inflammatory cytokines. Symptoms of HE range from subclinical to debilitating. HE can be difficult to treat and represents a large burden to patients, their caregivers, and the health-care system because of associated resource utilization. This review article provides an overview of the current understanding of the pathophysiology behind HE and where the current research and treatments are pointing toward.

Nontraditional Treatment of Hepatic Encephalopathy

The pathophysiology of hepatic encephalopathy (HE) is complex, with hyperammonemia playing a central role in its development. Traditional therapies for HE have targeted ammonia and include medications such as lactulose and rifaximin. Although these agents are considered standard of care, nontraditional treatments seek to affect other factors in the pathogenesis of HE. Finally, procedural therapies include albumin dialysis, shunt closure, and the ultimate cure for HE, which is liver transplant. The treatments discussed provide alternative options for patients who have failed standard of care. However, more high-quality studies are needed to routinely recommend many of these agents.

[Fecal Microbiota Transfer (FMT) in Germany - Status and Perspective]

INTRODUCTION

Fecal microbiota transfer (FMT) is a treatment to modulate the gastrointestinal microbiota. Its use in recurrent Clostridioides difficile infection (rCDI) is established throughout Europe and recommended in national and international guidelines. In Germany, the FMT is codeable in the hospital reimbursement system. A comprehensive survey on the frequency of use based on this coding is missing so far.

MATERIAL AND METHODOLOGY

Reports of the Institute for Hospital Remuneration (InEK), the Federal Statistical Office (DESTATIS), and hospital quality reports 2015-2021 were examined for FMT coding and evaluated in a structured expert consultation.

RESULTS

Between 2015 and 2021, 1,645 FMT procedures were coded by 175 hospitals. From 2016 to 2018, this was a median of 293 (274-313) FMT annually, followed by a steady decline in subsequent years to 119 FMT in 2021. Patients with FMT were 57.7% female, median age 74 years, and FMT was applied colonoscopically in 72.2%. CDI was the primary diagnosis in 86.8% of cases, followed by ulcerative colitis in 7.6%.

DISCUSSION

In Germany, FMT is used less frequently than in the European comparison. One application hurdle is the regulatory classification of FMT as a non-approved drug, which leads to significantly higher costs in manufacturing and administration and makes reimbursement difficult. The European Commission recently proposed a regulation to classify FMT as a transplant. This could prospectively change the regulatory situation of FMT in Germany and thus contribute to a nationwide offer of a therapeutic procedure recommended in guidelines.

Prophylaxis of hepatic encephalopathy: current and future drug targets

Hepatic encephalopathy is described by a broad spectrum of neurological and psychiatric aberrations resulting due to advanced liver dysfunction. It is a neurological disorder due to hepatic insufficiency and/or portosystemic shunts. Its clinical presentation includes neuropsychiatric dysfunction ranging from subclinical changes to comatose state. It is a sign of poor prognosis in cirrhotics with a high 1-year mortality. Each episode of hepatic encephalopathy leads to high hospitalization rate, poor prognosis and raised burden of healthcare. Primary prophylaxis is prevention of initial occurrence and secondary prophylaxis is prevention of reappearance of hepatic encephalopathy in subjects who had prior history. Early detection and management of triggers is very important in the treatment of hepatic encephalopathy. The initial choice of treatment is still lactulose, as it is effective in minimal, overt, and recurrent hepatic encephalopathy. Rifaximin is equally effective as lactulose in managing hepatic encephalopathy and is better tolerated. Branch chain amino acids are beneficial in subjects who are protein intolerant. L-ornithine L-aspartate and probiotics are also useful in the management of hepatic encephalopathy. Rifaximin along with lactulose is effective in managing overt and recurrent hepatic encephalopathy. Large portosystemic shunts embolization and liver transplant is efficacious in certain group of patients. Nutritional therapy and fecal microbiota transplantation are newer therapies for hepatic encephalopathy but the evidences are limited, more research is required to prove their efficacy. Involvement of hospital pharmacists, telemedicine, and providing education are also beneficial in managing hepatic encephalopathy.

Components from Curcuma longa (Turmeric) Against Hepatobiliary Diseases Based on Gut-Liver Axis: Pharmacotherapeutic Properties and Potential Clinical Applications

Turmeric is widely used worldwide, and there are many examples of its use in treating hepatobiliary diseases. The gut-liver axis is a bidirectional relationship between gut microorganisms and the liver that is closely related to the pathogenesis of hepatobiliary diseases. This review systematically summarizes the components of turmeric. It links the studies on turmeric affecting gut microorganisms to its effects on liver and biliary diseases to explain the potential mechanism of turmeric's regulation of the gut-liver axis. Besides, ethnopharmacology, phytochemicals, and clinical adverse events associated with turmeric have been researched. Furthermore, turmeric is a safe agent with good clinical efficacy and without apparent toxicity at a certain amount. By summarizing the influence of turmeric on the liver by regulating the gut-liver axis, especially the gut microbiota, it provides a preclinical basis for using turmeric as a safe and effective therapeutic agent for the prevention and treatment of hepatobiliary diseases based on the gut-liver axis. However, more efforts should be made to exploit its clinical application further.

Fecal microbiota transplantation for treatment of non-alcoholic fatty liver disease: Mechanism, clinical evidence, and prospect

The population of non-alcoholic fatty liver disease (NAFLD) patients along with relevant advanced liver disease is projected to continue growing, because currently no medications are approved for treatment. Fecal microbiota transplantation (FMT) is believed a novel and promising therapeutic approach based on the concept of the gut-liver axis in liver disease. There has been an increase in the number of pre-clinical and clinical studies evaluating FMT in NAFLD treatment, however, existing findings diverge on its effects. Herein, we briefly summarized the mechanism of FMT for NAFLD treatment, reviewed randomized controlled trials for evaluating its efficacy in NAFLD, and proposed the prospect of future trials on FMT.

Aminopeptidase O Protein mediates the association between Lachnospiraceae and appendicular lean mass

Objective

Investigating the causal relationship between Lachnospiraceae and Appendicular lean mass (ALM) and identifying and quantifying the role of Aminopeptidase O Protein (AOPEP) as a potential mediator.

Methods

The summary statistics data of gut microbiota composition from the largest available genome-wide association study (GWAS) meta-analysis conducted by the MiBioGen Consortium (n = 13,266). Appendicular lean mass data were obtained from the UK-Biobank (n = 450,243). We conducted bidirectional two-sample Mendelian randomization (MR) analysis using summary-level data from GWAS to investigate the causal relationship between Lachnospiraceae and ALM. Additionally, we employed a drug-targeted MR approach to assess the causal relationship between AOPEP and ALM. Finally, a two-step MR was employed to quantitatively estimate the proportion of the effect of Lachnospiraceae on ALM that is mediated by AOPEP. Cochran's Q statistic was used to quantify heterogeneity among instrumental variable estimates.

Results

In the MR analysis, it was found that an increase in genetically predicted Lachnospiraceae [OR = 1.031, 95% CI (1.011-1.051), P = 0.002] is associated with an increase in ALM. There is no strong evidence to suggest that genetically predicted ALM has an impact on Lachnospiraceae genus [OR = 1.437, 95% CI (0.785-2.269), P = 0.239]. The proportion of genetically predicted Lachnospiraceae mediated by AOPEP was 34.2% [95% CI (1.3%-67.1%)].

Conclusion

Our research reveals that increasing Lachnospiraceae abundance in the gut can directly enhance limb muscle mass and concurrently suppress AOPEP, consequently mitigating limb muscle loss. This supports the potential therapeutic modulation of gut microbiota for sarcopenia. Interventions such as drug treatments or microbiota transplantation, aimed at elevating Lachnospiraceae abundance and AOPEP inhibition, synergistically improve sarcopenia in the elderly, thereby enhancing the overall quality of life for older individuals.

Exploring the Relationship between Liver Disease, Bacterial Translocation, and Dysbiosis: Unveiling the Gut-Liver Axis

Background

The global burden of liver disease and cirrhosis has been progressively increasing in the last decade. The interplay between gut microbiota and immune system and the bidirectional relationship with the liver, known as the gut-liver axis, has arisen as a fundamental aspect of liver disease.

Summary

Alterations of the gut microbiome have been described and include both dysbiotic microbial signatures and intestinal bacterial overgrowth. The integrity of the intestinal epithelial barrier is essential for preventing the access of harmful substances and bacterial products into the host. Bacterial translocation due to altered host-microbiota interactions triggers local immune cell activation and facilitates a chronic inflammatory state that can ultimately lead to immune exhaustion, characteristic of cirrhosis. In cirrhosis, breakdown of the gut vascular barrier allows access of bacterial products to portal blood circulation and facilitates their influx into the liver, further contributing to disease progression.

Key Messages

A better understanding of the contributing factors to pathological bacterial translocation and the impact of dysbiosis in liver disease will lead to achieve innovative therapeutic strategies in cirrhosis.

Gut-Liver-Brain Axis and Alcohol Use Disorder: Treatment Potential of Fecal Microbiota Transplantation

PURPOSE

Chronic alcohol use is a major cause of liver damage and death. In the United States, multiple factors have led to low utilization of pharmacotherapy for alcohol use disorder (AUD), including lack of provider knowledge and comfort in prescribing medications for AUD. Alcohol consumption has direct effects on the gut microbiota, altering the diversity of bacteria and leading to bacterial overgrowth. Growing evidence suggests that alcohol's effects on the gut microbiome may contribute to increased alcohol consumption and progression of alcohol-associated liver disease (ALD). This article reviews human and preclinical studies investigating the role of fecal microbiota transplantation (FMT) in ameliorating alcohol-associated alterations to the liver, gut, and brain resulting in altered behavior; it also discusses the therapeutic potential of FMT.

SEARCH METHODS

For this narrative review, a literature search was conducted in September 2022 of PubMed, Web of Science Core Collection, and Google Scholar to identify studies published between January 2012 and September 2022. Search terms used included "fecal microbiota transplantation" and "alcohol."

SEARCH RESULTS

Most results of the literature search were review articles or articles on nonalcoholic fatty liver disease; these were excluded. Of the remaining empirical manuscripts, very few described clinical or preclinical studies that were directly investigating the effects of FMT on alcohol drinking or related behaviors. Ultimately, 16 studies were included in the review.

DISCUSSION AND CONCLUSIONS

The literature search identified only a few studies that were directly investigating the effect of FMT on ALD or alcohol drinking and related behaviors. Largely proof-of-concept studies, these findings demonstrate that alcohol can alter the gut microbiome and that the microbiome can be transferred between humans and rodents to alter affective behaviors frequently associated with increased alcohol use. Other studies have shown promise of FMT or other probiotic supplementation in alleviating some of the symptoms associated with ALD and drinking. These results show that the implementation of FMT as a therapeutic approach is still in the investigatory stages.

Role of fecal microbiota transplant in management of hepatic encephalopathy: Current trends and future directions

Fecal microbiota transplantation (FMT) offers a potential treatment avenue for hepatic encephalopathy (HE) by leveraging beneficial bacterial displacement to restore a balanced gut microbiome. The prevalence of HE varies with liver disease severity and comorbidities. HE pathogenesis involves ammonia toxicity, gut-brain communication disruption, and inflammation. FMT aims to restore gut microbiota balance, addressing these factors. FMT's efficacy has been explored in various conditions, including HE. Studies suggest that FMT can modulate gut microbiota, reduce ammonia levels, and alleviate inflammation. FMT has shown promise in alcohol-associated, hepatitis B and C-associated, and non-alcoholic fatty liver disease. Benefits include improved liver function, cognitive function, and the slowing of disease progression. However, larger, controlled studies are needed to validate its effectiveness in these contexts. Studies have shown cognitive improvements through FMT, with potential benefits in cirrhotic patients. Notably, trials have demonstrated reduced serious adverse events and cognitive enhancements in FMT arms compared to the standard of care. Although evidence is promising, challenges remain: Limited patient numbers, varied dosages, administration routes, and donor profiles. Further large-scale, controlled trials are essential to establish standardized guidelines and ensure FMT's clinical applications and efficacy. While FMT holds potential for HE management, ongoing research is needed to address these challenges, optimize protocols, and expand its availability as a therapeutic option for diverse hepatic conditions.

Microbiota-gut-liver-brain axis and hepatic encephalopathy

Hepatic encephalopathy (HE) is a clinical manifestation of neurological and psychiatric abnormalities that are caused by complications of liver dysfunction including hyperammonemia, hyperuricemia, and portal hypertension. Accumulating evidence suggests that HE could be reversed through therapeutic modifications of gut microbiota. Multiple preclinical and clinical studies have indicated that gut microbiome affects the physiological function of the liver, such as the regulation of metabolism, secretion, and immunity, through the gut-liver crosstalk. In addition, gut microbiota also influences the brain through the gut-brain crosstalk, altering its physiological functions including the regulation of the immune, neuroendocrine, and vagal pathways. Thus, key molecules that are involved in the microbiota-gut-liver-brain axis might be able to serve as clinical biomarkers for early diagnosis of HE, and could be effective therapeutic targets for clinical interventions. In this review, we summarize the pathophysiology of HE and further propose approaches modulating the microbiota-gut-liver-brain axis in order to provide a comprehensive understanding of the prevention and potential clinical treatment for HE with a microbiota-targeted therapy.

Oral fecal transplantation enriches Lachnospiraceae and butyrate to mitigate acute liver injury

While fecal microbiota transplantation (FMT) shows promise in treating human diseases, oral capsule FMT is more accepted and accessible to patients. However, microbe selection in the upper gastrointestinal tract (UGIT) through oral administration remains unclear. Here, we demonstrate that short-term oral fecal gavage (OFG) alleviates acetaminophen-induced acute liver injury (AILI) in mice, regardless of the divergent effects of commensal gut microbes. Pasteurized fecal gavage yields similar therapeutic effects. OFG enriches gut Lachnospiraceae and butyrate compared to donor feces. Butyrate mitigates AILI-induced ferroptosis via AMPK-ULK1-p62 signaling to simultaneously induce mitophagy and Nrf2 antioxidant responses. Combined N-acetylcysteine and butyrate administration significantly improves AILI mouse survival rates. These observations indicate the significance of the UGIT in modulating the implanted fecal microbes through oral administration and its potential biological and clinical impacts. Our findings also highlight a possible strategy for applying microbial metabolites to treat acute liver injury.

Multi-omics approaches to studying gastrointestinal microbiome in the context of precision medicine and machine learning

The human gastrointestinal (gut) microbiome plays a critical role in maintaining host health and has been increasingly recognized as an important factor in precision medicine. High-throughput sequencing technologies have revolutionized -omics data generation, facilitating the characterization of the human gut microbiome with exceptional resolution. The analysis of various -omics data, including metatranscriptomics, metagenomics, glycomics, and metabolomics, holds potential for personalized therapies by revealing information about functional genes, microbial composition, glycans, and metabolites. This multi-omics approach has not only provided insights into the role of the gut microbiome in various diseases but has also facilitated the identification of microbial biomarkers for diagnosis, prognosis, and treatment. Machine learning algorithms have emerged as powerful tools for extracting meaningful insights from complex datasets, and more recently have been applied to metagenomics data via efficiently identifying microbial signatures, predicting disease states, and determining potential therapeutic targets. Despite these rapid advancements, several challenges remain, such as key knowledge gaps, algorithm selection, and bioinformatics software parametrization. In this mini-review, our primary focus is metagenomics, while recognizing that other -omics can enhance our understanding of the functional diversity of organisms and how they interact with the host. We aim to explore the current intersection of multi-omics, precision medicine, and machine learning in advancing our understanding of the gut microbiome. A multidisciplinary approach holds promise for improving patient outcomes in the era of precision medicine, as we unravel the intricate interactions between the microbiome and human health.

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.

A Comprehensive Overview of the Past, Current, and Future Randomized Controlled Trials in Hepatic Encephalopathy

Background: Hepatic encephalopathy (HE) caused by cirrhosis has severe consequences on an individual's lifespan, leading to long-term liver complications and potentially life-threatening outcomes. Despite recent interest in this condition, the effectiveness of secondary prophylaxis involving rixafimin, lactulose, or L-ornithine L-aspartate (LOLA) may be hindered by the unique microbial profiles each patient possesses. Methods: Thus, in this manuscript, we aimed to search, identify, and gather all randomized controlled trials (RCTs) published between 2000-2023 (November) in four major academic databases such as PubMed, ISI Web of Science, Scopus, and ScienceDirect by using a controlled terminology and web strings that reunite six main keywords. We complementarily retrieved data on the ongoing RCTs. Results: Regardless of the relatively high number of results displayed (n = 75), 46.66% (n = 35) were initially deemed eligible after the first evaluation phase after removing duplicates, n = 40 (53.34%). At the second assessment stage, we eliminated 11.42% (n = 4) studies, of which n = 22 finally met the eligibility criteria to be included in the main body of the manuscript. In terms of RCTs, otherwise found in distinct stages of development, n = 3 target FMT and n = 1 probiotics. Conclusions: Although we benefit from the necessary information and technology to design novel strategies for microbiota, only probiotics and synbiotics have been extensively studied in the last decade compared to FMT.

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.

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.

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 in Liver Cirrhosis

The human gastrointestinal tract houses a diverse array of probiotic and pathogenic bacteria and any alterations in this microbial composition can exert a significant influence on an individual's well-being. It is well-established that imbalances in the gut microbiota play a pivotal role in the development of liver diseases. In light of this, a new adjuvant therapy for liver diseases could be regulating the intestinal microbiota. Through fecal microbiota transplantation, patients whose microbiomes are compromised are treated with stool from healthy donors in an attempt to restore a normal microbiome and alleviate their symptoms. A review of cross-sectional studies and case reports suggests that fecal microbiota transplants may offer effective treatment for chronic liver diseases. Adding to the potential of this emerging therapy, recent research has indicated that fecal microbiota transplantation holds promise as a therapeutic approach specifically for liver cirrhosis. By introducing a diverse range of beneficial microorganisms into the gut, this innovative treatment aims to address the microbial imbalances often observed in cirrhotic patients. While further validation is still required, these preliminary findings highlight the potential impact of fecal microbiota transplantation as a novel and targeted method for managing liver cirrhosis. We aimed to summarize the current state of understanding regarding this procedure, as a new therapeutic method for liver cirrhosis, as well as to explain its clinical application and future potential.

Probiotic management and inflammatory factors as a novel treatment in cirrhosis: A systematic review and meta-analysis

The interaction between intestinal microecological dysregulation, altered inflammatory factors, and cirrhosis is unclear. The aim of this systematic review and meta-analysis was to synthesize the results of previous studies to assess the efficacy of probiotics in the treatment of cirrhosis and their effect on inflammatory factors, as well as to explore the relationship between gut microecological dysregulation and liver disease to gain a deeper understanding of this interaction. Up to December 2022, eligible studies were identified by searching the following databases: National Knowledge Infrastructure (CNKI), Wanfang Data, Web of Science, PubMed, Embase, Medline, and the Cochrane Library. Statistical analysis was performed using software RevMan Version 5.4. A total of 33 eligible randomized controlled trials were included in the study, and data on probiotic strains, duration of intervention, measures in the control group, and outcomes were extracted and evaluated. Compared to the control group, the experimental group had significant improvements in overall efficacy. The results of the meta-analysis revealed that probiotic use significantly decreased biochemical parameters for liver function, including aspartate transaminase, alanine aminotransferase, and total bilirubin. Similar result was obtained in interleukin-6, tumor necrosis factor-α, and endotoxin. However, probiotic intervention did not significantly affect interleukin-2 and interleukin-10. The current meta-analysis illustrates that probiotic supplementation reduces inflammatory markers and biochemical parameters for liver function in patients with cirrhosis, suggesting that probiotic management may be a novel treatment for cirrhosis. Furthermore, the interaction of the gut microbiota, associated metabolites, and inflammation factors with cirrhosis may provide a promising therapeutic target for the pharmacological and clinical treatment of cirrhosis.

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.

From-Toilet-to-Freezer: A Review on Requirements for an Automatic Protocol to Collect and Store Human Fecal Samples for Research Purposes

The composition, viability and metabolic functionality of intestinal microbiota play an important role in human health and disease. Studies on intestinal microbiota are often based on fecal samples, because these can be sampled in a non-invasive way, although procedures for sampling, processing and storage vary. This review presents factors to consider when developing an automated protocol for sampling, processing and storing fecal samples: donor inclusion criteria, urine-feces separation in smart toilets, homogenization, aliquoting, usage or type of buffer to dissolve and store fecal material, temperature and time for processing and storage and quality control. The lack of standardization and low-throughput of state-of-the-art fecal collection procedures promote a more automated protocol. Based on this review, an automated protocol is proposed. Fecal samples should be collected and immediately processed under anaerobic conditions at either room temperature (RT) for a maximum of 4 h or at 4 °C for no more than 24 h. Upon homogenization, preferably in the absence of added solvent to allow addition of a buffer of choice at a later stage, aliquots obtained should be stored at either -20 °C for up to a few months or -80 °C for a longer period-up to 2 years. Protocols for quality control should characterize microbial composition and viability as well as metabolic functionality.

A meta-analysis of microbiome therapies for hepatic encephalopathy

Microbiome therapies may be reported to be effective in hepatic encephalopathy (HE). We thus did a meta-analysis of randomized controlled trials to assess the effect of microbiome therapies for HE. We systematically searched PubMed, Web of Science, EMBASE, and Cochrane Library for randomized controlled trials that compared the different treatments for HE including probiotics, symbiotics, and fecal microbiota transplant (FMT). Meta-analysis was performed to calculate pooled odds ratios (ORs) with corresponding 95% confidence intervals (CIs). Twenty-one studies met our inclusion criteria (N = 1746 participants). Probiotics, synbiotics and FMT significantly reversed minimal HE (MHE) (OR: 0.41, 95% CI: 0.19-0.90, P = 0.03), reduced overt HE (OHE) development (OR, 0.41; 95% CI: 0.28-0.61 P < 0.00001)and the frequency of serious adverse events(SAEs) (OR:0.14, 95% CI: 0.04-0.47, P = 0.001), meanwhile decreased ammonia levels (WMD: -9.26, 95% CI: -16.92 to -1.61; P = 0.02), NCT level (MD = -4.41, 95% CI: -0.87 to -0.22, P = 0.04) and hospitalization rates (OR, 0.38; 95% CI: 0.19-0.79, P = 0.009) compared with placebo/no treatment. Finally, we conclude that microbiome therapies were more effective in improving MHE and preventing progression to OHE, reducing the frequency of SAEs, and decreasing ammonia levels, NCT level, and hospitalization rates when compared to placebo/no treatment.

The Role of the Gastrointestinal Microbiome in Liver Disease

Liver disease is a major global health problem leading to approximately two million deaths a year. This is the consequence of a number of aetiologies, including alcohol-related, metabolic-related, viral infection, cholestatic and immune disease, leading to fibrosis and, eventually, cirrhosis. No specific registered antifibrotic therapies exist to reverse liver injury, so current treatment aims at managing the underlying factors to mitigate the development of liver disease. There are bidirectional feedback loops between the liver and the rest of the gastrointestinal tract via the portal venous and biliary systems, which are mediated by microbial metabolites, specifically short-chain fatty acids (SCFAs) and secondary bile acids. The interaction between the liver and the gastrointestinal microbiome has the potential to provide a novel therapeutic modality to mitigate the progression of liver disease and its complications. This review will outline our understanding of hepatic fibrosis, liver disease, and its connection to the microbiome, which may identify potential therapeutic targets or strategies to mitigate liver disease.

Gut Microbiome-Centered Therapies for Alcohol-Associated Liver Disease

Globally, liver disease caused by alcohol is becoming more prevalent each year. Misuse of alcohol causes a spectrum of liver diseases, such as liver steatosis, steatohepatitis, fibrosis, cirrhosis, and hepatocellular carcinoma. The cornerstone of treatment is abstinence from alcohol. In spite of this, available treatment for alcohol-associated liver disease (ALD) shows limited effectiveness currently. There are numerous ways in which alcohol disrupts the gut-liver axis, including dysbiosis of the gut microbiome, disruption of mucus and epithelial cell barriers, impaired production of antimicrobial molecules, and dysfunction of the immune system, causing translocation of viable microbes and microbial products to the liver and systemic circulation. Microbial exposure results in not only inflammation and progression of liver disease but also infections in late-stage ALD. This led scientists to focus their therapeutic strategies and targets for ALD on the gut microbiome. Throughout this review, we address the role of gut microbiome-centered therapeutic approaches for ALD focusing predominantly on randomized controlled trials. We will summarize the latest clinical trials using probiotics, antibiotics, and fecal microbial transplants in modulating the gut-liver axis and for improvement of ALD.

Sarcopenia in cirrhosis: Prospects for therapy targeted to gut microbiota

Decreased muscle mass and function, also known as sarcopenia, is common in patients with cirrhosis and is associated with a poor prognosis. Although the pathogenesis of this disorder has not been fully elucidated, a disordered gut-muscle axis probably plays an important role. Decreased barrier function of the gut and liver, gut dysbiosis, and small intestinal bacterial overgrowth (SIBO) can lead to increased blood levels of ammonia, lipopolysaccharides, pro-inflammatory mediators, and myostatin. These factors have complex negative effects on muscle mass and function. Drug interventions that target the gut microbiota (long-term use of rifaximin, lactulose, lactitol, or probiotics) positively affect most links of the compromised gut-muscle axis in patients with cirrhosis by decreasing the levels of hyperammonemia, bacterial translocation, and systemic inflammation and correcting gut dysbiosis and SIBO. However, although these drugs are promising, they have not yet been investigated in randomized controlled trials specifically for the treatment and prevention of sarcopenia in patients with cirrhosis. No data exist on the effects of fecal transplantation on most links of gut-muscle axis in cirrhosis; however, the results of animal experimental studies are promising.

Hepatic encephalopathy: investigational drugs in preclinical and early phase development

INTRODUCTION

Hepatic encephalopathy (HE) is a neuropsychiatric syndrome, in patients with liver disease, which affects life quality and span. Current treatments are lactulose or rifaximin, acting on gut microbiota. Treatments aiming ammonia levels reduction have been tested with little success.

AREAS COVERED

Pre-clinical research shows that the process inducing HE involves sequentially: liver failure, altered microbiome, hyperammonemia, peripheral inflammation, changes in immunophenotype and extracellular vesicles and neuroinflammation, which alters neurotransmission impairing cognitive and motor function. HE may be reversed using drugs acting at any step: modulating microbiota with probiotics or fecal transplantation; reducing peripheral inflammation with anti-TNFα, autotaxin inhibitors or silymarin; reducing neuroinflammation with sulforaphane, p38 MAP kinase or phosphodiesteras 5 inhibitors, antagonists of sphingosine-1-phosphate receptor 2, enhancing meningeal lymphatic drainage or with extracellular vesicles from mesenchymal stem cells; reducing GABAergic neurotransmission with indomethacin or golexanolone.

EXPERT OPINION

A factor limiting the progress of HE treatment is the lack of translation of research advances into clinical trials. Only drugs acting on microbiota or ammonia reduction have been tested in patients. It is urgent to change the mentality on how to approach HE treatment to develop clinical trials to assess drugs acting on the immune system/peripheral inflammation, neuroinflammation or neurotransmission to improve HE.

Update in the Treatment of the Complications of Cirrhosis

Cirrhosis consists of 2 main stages: compensated and decompensated, the latter defined by the development/presence of ascites, variceal hemorrhage, and hepatic encephalopathy. The survival rate is entirely different, depending on the stage. Treatment with nonselective β-blockers prevents decompensation in patients with clinically significant portal hypertension, changing the previous paradigm based on the presence of varices. In patients with acute variceal hemorrhage at high risk of failure with standard treatment (defined as those with a Child-Pugh score of 10-13 or those with a Child-Pugh score of 8-9 with active bleeding at endoscopy), a pre-emptive transjugular intrahepatic portosystemic shunt (TIPS) improves the mortality rate and has become the standard of care in many centers. In patients with bleeding from gastrofundal varices, retrograde transvenous obliteration (in those with a gastrorenal shunt) and/or variceal cyanoacrylate injection have emerged as alternatives to TIPS. In patients with ascites, emerging evidence suggests that TIPS might be used earlier, before strict criteria for refractory ascites are met. Long-term albumin use is under assessment for improving the prognosis of patients with uncomplicated ascites and confirmatory studies are ongoing. Hepatorenal syndrome is the least common cause of acute kidney injury in cirrhosis, and first-line treatment is the combination of terlipressin and albumin. Hepatic encephalopathy has a profound impact on the quality of life of patients with cirrhosis. Lactulose and rifaximin are first- and second-line treatments for hepatic encephalopathy, respectively. Newer therapies such as L-ornithine L-aspartate and albumin require further assessment.

Gut Microbiota and Neuroinflammation in Acute Liver Failure and Chronic Liver Disease

Acute liver failure and chronic liver disease are associated with a wide spectrum of neurological changes, of which the best known is hepatic encephalopathy (HE). Historically, hyperammonemia, causing astrocyte swelling and cerebral oedema, was considered the main etiological factor in the pathogenesis of cerebral dysfunction in patients with acute and/or chronic liver disease. However, recent studies demonstrated a key role of neuroinflammation in the development of neurological complications in this setting. Neuroinflammation is characterized by activation of microglial cells and brain secretion of pro-inflammatory cytokines, such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6, which alter neurotransmission, leading to cognitive and motor dysfunction. Changes in the gut microbiota resulting from liver disease play a crucial role in the pathogenesis of neuroinflammation. Dysbiosis and altered intestinal permeability, resulting in bacterial translocation and endotoxemia, are responsible for systemic inflammation, which can spread to brain tissue and trigger neuroinflammation. In addition, metabolites derived from the gut microbiota can act on the central nervous system and facilitate the development of neurological complications, exacerbating clinical manifestations. Thus, strategies aimed at modulating the gut microbiota may be effective therapeutic weapons. In this review, we summarize the current knowledge on the role of the gut-liver-brain axis in the pathogenesis of neurological dysfunction associated with liver disease, with a particular focus on neuroinflammation. In addition, we highlight emerging therapeutic approaches targeting the gut microbiota and inflammation in this clinical setting.

Gut Microbiota and Antibiotic Treatments for the Main Non-Oncologic Hepato-Biliary-Pancreatic Disorders

The gut microbiota is a pivotal actor in the maintenance of the balance in the complex interconnections of hepato-biliary-pancreatic system. It has both metabolic and immunologic functions, with an influence on the homeostasis of the whole organism and on the pathogenesis of a wide range of diseases, from non-neoplastic ones to tumorigenesis. The continuous bidirectional metabolic communication between gut and hepato-pancreatic district, through bile ducts and portal vein, leads to a continuous interaction with translocated bacteria and their products. Chronic liver disease and pancreatic disorders can lead to reduced intestinal motility, decreased bile acid synthesis and intestinal immune dysfunction, determining a compositional and functional imbalance in gut microbiota (dysbiosis), with potentially harmful consequences on the host's health. The modulation of the gut microbiota by antibiotics represents a pioneering challenge with striking future therapeutic opportunities, even in non-infectious diseases. In this setting, antibiotics are aimed at harmonizing gut microbial function and, sometimes, composition. A more targeted and specific approach should be the goal to pursue in the future, tailoring the treatment according to the type of microbiota modulation to be achieved and using combined strategies.

Mycotoxin deoxynivalenol-induced intestinal flora disorders, dysfunction and organ damage in broilers and pigs

Deoxynivalenol (DON) is a common environmental contaminant that causes food refusal and growth retardation in animals. DON targets the intestine and is hazardous to animal, however, it is not clear whether its effect on animals is consistent. Chickens and pigs are the two main animals affected by DON exposure with different susceptibilities. In this study, we found that DON inhibited animal growth and caused damage to the intestine, liver and kidney. DON caused intestinal flora disorders in both chickens and pigs, such as changes of flora diversity and the relative abundance of dominant phyla. Functional analysis showed that changes in the intestinal flora induced by DON were mainly related to metabolic and digestive functions, indicated that the intestinal flora may be associated with the DON-induced intestinal dysfunction. Comparative analysis of differentially altered bacteria suggested that Prevotella may play an important role in maintaining intestinal health, and the presence of differentially altered bacteria in the two animals suggested that DON may have different toxicity modes in animals. In summary, we confirmed the multi-organ toxicity of DON in two major livestock and poultry animals, and speculated that the intestinal flora may be related to the toxic damage caused by DON through species comparison analysis.

Hepatic encephalopathy increases the risk for mortality and hospital readmission in decompensated cirrhotic patients: a prospective multicenter study

Introduction

Hepatic encephalopathy (HE) affects the survival and quality of life of patients with cirrhosis. However, longitudinal data on the clinical course after hospitalization for HE are lacking. The aim was to estimate mortality and risk for hospital readmission of cirrhotic patients hospitalized for HE.

Methods

We prospectively enrolled 112 consecutive cirrhotic patients hospitalized for HE (HE group) at 25 Italian referral centers. A cohort of 256 patients hospitalized for decompensated cirrhosis without HE served as controls (no HE group). After hospitalization for HE, patients were followed-up for 12 months until death or liver transplant (LT).

Results

During follow-up, 34 patients (30.4%) died and 15 patients (13.4%) underwent LT in the HE group, while 60 patients (23.4%) died and 50 patients (19.5%) underwent LT in the no HE group. In the whole cohort, age (HR 1.03, 95% CI 1.01-1.06), HE (HR 1.67, 95% CI 1.08-2.56), ascites (HR 2.56, 95% CI 1.55-4.23), and sodium levels (HR 0.94, 95% CI 0.90-0.99) were significant risk factors for mortality. In the HE group, ascites (HR 5.07, 95% CI 1.39-18.49) and BMI (HR 0.86, 95% CI 0.75-0.98) were risk factors for mortality, and HE recurrence was the first cause of hospital readmission.

Conclusion

In patients hospitalized for decompensated cirrhosis, HE is an independent risk factor for mortality and the most common cause of hospital readmission compared with other decompensation events. Patients hospitalized for HE should be evaluated as candidates for LT.

Therapeutic possibilities of gut microbiota modulation in acute decompensation of liver cirrhosis

The formation of liver cirrhosis (LC) is an unfavorable event in the natural history of chronic liver diseases and with the development of portal hypertension and/or impaired liver function can cause a fatal outcome. Decompensation of LC is considered the most important stratification variable for the risk of death. It is currently postulated that decompensation of LC occurs through an acute (including acute-on-chronic liver failure) and non-acute pathway. Acute decompensation of LC is accompanied by the development of life-threatening complications, characterized by an unfavorable prognosis and high mortality. Progress in understanding the underlying molecular mechanisms has led to the search for new interventions, drugs, and biological substances that can affect key links in the pathogenesis of acute decompensation in LC, for example the impaired gut-liver axis and associated systemic inflammation. Given that particular alterations in the composition and function of gut microbiota play a crucial role here, the study of the therapeutic possibilities of its modulation has emerged as one of the top concerns in modern hepatology. This review summarized the investigations that describe the theoretical foundations and therapeutic potential of gut microbiota modulation in acute decompensation of LC. Despite the encouraging preliminary data, the majority of the suggested strategies have only been tested in animal models or in preliminary clinical trials; additional multicenter randomized controlled trials must demonstrate their efficacy in larger patient populations.

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 Implication of the Gut Microbiome in Heart Failure

Heart failure is a worldwide health problem with important consequences for the overall wellbeing of affected individuals as well as for the healthcare system. Over recent decades, numerous pieces of evidence have demonstrated that the associated gut microbiota represent an important component of human physiology and metabolic homeostasis, and can affect one's state of health or disease directly, or through their derived metabolites. The recent advances in human microbiome studies shed light on the relationship between the gut microbiota and the cardiovascular system, revealing its contribution to the development of heart failure-associated dysbiosis. HF has been linked to gut dysbiosis, low bacterial diversity, intestinal overgrowth of potentially pathogenic bacteria and a decrease in short chain fatty acids-producing bacteria. An increased intestinal permeability allowing microbial translocation and the passage of bacterial-derived metabolites into the bloodstream is associated with HF progression. A more insightful understanding of the interactions between the human gut microbiome, HF and the associated risk factors is mandatory for optimizing therapeutic strategies based on microbiota modulation and offering individualized treatment. The purpose of this review is to summarize the available data regarding the influence of gut bacterial communities and their derived metabolites on HF, in order to obtain a better understanding of this multi-layered complex relationship.

Active Clinical Trials in Hepatic Encephalopathy: Something Old, Something New and Something Borrowed

Hepatic encephalopathy (HE) is a potentially reversible neurocognitive syndrome that occurs in patients with acute or chronic liver disease. Currently, most of the therapies for HE aim to reduce ammonia production or increase its elimination. To date, only two agents have been approved as treatments for HE: lactulose and rifaximin. Many other drugs have also been used, but data to support their use are limited, preliminary or lacking. The aim of this review is to provide an overview and discussion of the current development of treatments for HE. Data from ongoing clinical trials in HE were obtained from the ClinicalTrials.gov website, and a breakdown analysis of studies that were active on August 19th, 2022, was performed. Seventeen registered and ongoing clinical trials for therapeutics targeting HE were identified. More than 75% of these agents are in phase II (41.2%) or in phase III (34.7%). Among them, there are many old acquaintances in the field, such as lactulose and rifaximin, some new entries such as fecal microbiota transplantation and equine anti-thymocyte globulin, an immunosuppressive agent, but also some therapies borrowed from other conditions, such as rifamycin SV MMX and nitazoxanide, two antimicrobial agents FDA approved for the treatment of some types of diarrheas or VE303 and RBX7455, two microbiome restoration therapies, currently used as treatment of high-risk Clostridioides difficile infections. If working, some of these drugs could soon be used as valid alternatives to current therapies when ineffective or be approved as novel therapeutic approaches to improve the quality of life of HE patients.

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.

Gut microbiome-brain-cirrhosis axis

Cirrhosis is characterized by inflammation, degeneration, and fibrosis of liver tissue. Along with being the most common cause of liver failure and liver transplant, cirrhosis is a significant risk factor for several neuropsychiatric conditions. The most common of these is HE, which is characterized by cognitive and ataxic symptoms, resulting from the buildup of metabolic toxins with liver failure. However, cirrhosis patients also show a significantly increased risk for neurodegenerative diseases such as Alzheimer and Parkinson diseases, and for mood disorders such as anxiety and depression. In recent years, more attention has been played to communication between the ways the gut and liver communicate with each other and with the central nervous system, and the way these organs influence each other's function. This bidirectional communication has come to be known as the gut-liver-brain axis. The gut microbiome has emerged as a key mechanism affecting gut-liver, gut-brain, and brain-liver communication. Clinical studies and animal models have demonstrated the significant patterns of gut dysbiosis when cirrhosis is present, both with or without concomitant alcohol use disorder, and have provided compelling evidence that this dysbiosis also influences the cognitive and mood-related behaviors. In this review, we have summarized the pathophysiological and cognitive effects associated with cirrhosis, links to cirrhosis-associated disruption of the gut microbiome, and the current evidence from clinical and preclinical studies for the modulation of the gut microbiome as a treatment for cirrhosis and associated neuropsychiatric conditions.

Hepatic encephalopathy - recent advances in treatment and diagnosis

INTRODUCTION

Hepatic encephalopathy (HE) is a peculiar kind of brain dysfunction typical of liver cirrhosis characterized by nonspecific neurological and psychiatric manifestations. HE ranges from minimal hepatic encephalopathy (MHE) to the most severe form characterized by alteration of consciousness or coma (overt HE, OHE). Once the diagnosis of OHE is made, every effort to identify and correct the precipitating cause is essential for the resolution of symptoms. Clinical studies that assessed the prevalence and incidence of any type of HE (MHE and OHE) in patients affected by cirrhosis were included in this review. No language, publication date, or publication status restrictions were imposed. The studies were identified by searching electronic databases (PubMed and SCOPUS).

AREAS COVERED

The most widely empirical pharmacological approach consists of non-absorbable antibiotics (rifaximin) and non-absorbable disaccharides (lactulose, lactitol per os and per enemas). Other agents (including branched-chain amino acids, probiotics, other antibiotics, or intravenous L-ornithine L-aspartate) are available, but the evidence supporting their efficacy remains under debate.

EXPERT OPINION

Gray areas and future needs remain the therapeutic approach to MHE and issues in the design of therapeutic studies for HE which have been extensively discussed in this review.

Cellular Pathogenesis of Hepatic Encephalopathy: An Update

Hepatic encephalopathy (HE) is a neuropsychiatric syndrome derived from metabolic disorders due to various liver failures. Clinically, HE is characterized by hyperammonemia, EEG abnormalities, and different degrees of disturbance in sensory, motor, and cognitive functions. The molecular mechanism of HE has not been fully elucidated, although it is generally accepted that HE occurs under the influence of miscellaneous factors, especially the synergistic effect of toxin accumulation and severe metabolism disturbance. This review summarizes the recently discovered cellular mechanisms involved in the pathogenesis of HE. Among the existing hypotheses, ammonia poisoning and the subsequent oxidative/nitrosative stress remain the mainstream theories, and reducing blood ammonia is thus the main strategy for the treatment of HE. Other pathological mechanisms mainly include manganese toxicity, autophagy inhibition, mitochondrial damage, inflammation, and senescence, proposing new avenues for future therapeutic interventions.

Alcohol, Inflammation, and Microbiota in Alcoholic Liver Disease

Alcoholic liver disease (ALD) is a consequence of excessive alcohol use. According to many studies, alcohol represents a significant socioeconomic and health risk factor in today's population. According to data from the World Health Organization, there are about 75 million people who have alcohol disorders, and it is well known that its use leads to serious health problems. ALD is a multimodality spectrum that includes alcoholic fatty liver disease (AFL) and alcoholic steatohepatitis (ASH), consequently leading to liver fibrosis and cirrhosis. In addition, the rapid progression of alcoholic liver disease can lead to alcoholic hepatitis (AH). Alcohol metabolism produces toxic metabolites that lead to tissue and organ damage through an inflammatory cascade that includes numerous cytokines, chemokines, and reactive oxygen species (ROS). In the process of inflammation, mediators are cells of the immune system, but also resident cells of the liver, such as hepatocytes, hepatic stellate cells, and Kupffer cells. These cells are activated by exogenous and endogenous antigens, which are called pathogen and damage-associated molecular patterns (PAMPs, DAMPs). Both are recognized by Toll-like receptors (TLRs), which activation triggers the inflammatory pathways. It has been proven that intestinal dysbiosis and disturbed integrity of the intestinal barrier perform a role in the promotion of inflammatory liver damage. These phenomena are also found in chronic excessive use of alcohol. The intestinal microbiota has an important role in maintaining the homeostasis of the organism, and its role in the treatment of ALD has been widely investigated. Prebiotics, probiotics, postbiotics, and symbiotics represent therapeutic interventions that can have a significant effect on the prevention and treatment of ALD.