Dynamic Changes of the Fungal Microbiome in Alcohol Use Disorder

Intestinal Microbes, Metabolites, and Hormones in Alcohol-Associated Liver Disease

Alcohol-associated liver disease (ALD)-encompassing conditions including steatosis, fibrosis, cirrhosis, and hepatocellular carcinoma-refers to hepatic damage arising from excessive or hazardous alcohol consumption, and is now recognized as a significant global health burden. Although the mechanisms underlying ALD remain incompletely understood, several pathways have been substantiated over the last five decades, notably the involvement of intestinal microorganisms and the involvement of the gut-liver axis in alcohol metabolism and ALD pathogenesis. Ethanol intake disrupts the intestinal microbial balance and compromises the gut barrier, resulting in increased permeability to microbial products. The subsequent translocation of microbial metabolites and other antigenic substances to the liver activates hepatic immune responses, thereby contributing to liver injury. In addition, gastrointestinal hormones are also implicated in ALD progression through various mechanisms. Although no therapies for ALD have been approved by the Food and Drug Administration, various therapeutic strategies targeting the intestinal microbiota and gut barrier have been identified. In conclusion, this review discusses the role of the gut-liver axis in alcohol metabolism and ALD pathogenesis and explores the emerging therapeutic strategies.

Unlocking the gut-liver axis: microbial contributions to the pathogenesis of metabolic-associated fatty liver disease

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a complex metabolic disorder characterized by hepatic lipid accumulation and subsequent inflammation. This condition is closely linked to metabolic syndrome and obesity, with its prevalence rising due to sedentary lifestyles and high-calorie diets. The pathogenesis of MAFLD involves multiple factors, including insulin resistance, lipotoxicity, oxidative stress, and inflammatory responses. The gut microbiota plays a crucial role in MAFLD development, with dysbiosis contributing to liver inflammation through various mechanisms, such as enhanced intestinal permeability and the translocation of bacterial products like lipopolysaccharide (LPS). Microbial metabolites, including short-chain fatty acids (SCFAs) and bile acids, influence hepatic function and immune responses, with potential implications for disease progression. Specific gut microbiome signatures have been identified in MAFLD patients, offering potential diagnostic and therapeutic targets. Moreover, gut-derived toxins, such as endotoxins, lipopolysaccharides, trimethylamine-N-oxide and bacterial metabolites, significantly influence liver damage and inflammation, highlighting the complex interplay between the gut microbiome and hepatic health. This review comprehensively examines the complex interplay between the gut microbiota and MAFLD, focusing on underlying pathogenic mechanisms, potential biomarkers, and emerging microbiome-targeted therapeutic strategies for disease management.

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

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

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

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

Role of Fungi in Tumorigenesis: Promises and Challenges

The mycobiome plays a key role in the host immune responses in homeostasis and inflammation. Recent studies suggest that an imbalance in the gut's fungi contributes to chronic, noninfectious diseases such as obesity, metabolic disorders, and cancers. Pathogenic fungi can colonize specific organs, and the gut mycobiome has been linked to the development and progression of various cancers, including colorectal, breast, head and neck, and pancreatic cancers. Some fungal species can promote tumorigenesis by triggering the complement system. However, in immunocompromised patients, fungi can also inhibit this activation and establish life-threatening infections. Interestingly, the interaction of the fungi and bacteria can also induce unique host immune responses. Recent breakthroughs and advancements in high-throughput sequencing of the gut and tumor mycobiomes are highlighting novel diagnostic and therapeutic opportunities for cancer. We discuss the latest developments in the field of cancer and the mycobiome and the potential benefits and challenges of antifungal therapies.

Fungal symbiont transmitted by free-living mice promotes type 2 immunity

The gut mycobiota is crucial for intestinal homeostasis and immune function1. Yet its variability and inconsistent fungal colonization of laboratory mice hinders the study of the evolutionary and immune processes that underpin commensalism2,3. Here, we show that Kazachstania pintolopesii is a fungal commensal in wild urban and rural mice, with an exceptional ability to colonize the mouse gastrointestinal tract and dominate the gut mycobiome. Kazachstania pintolopesii colonization occurs in a bacteria-independent manner, results in enhanced colonization resistance to other fungi and is shielded from host immune surveillance, allowing commensal presence. Following changes in the mucosal environment, K. pintolopesii colonization triggers a type 2 immune response in mice and induces gastrointestinal eosinophilia. Mechanistically, we determined that K. pintolopesii activates type 2 immunity via the induction of epithelial IL-33 and downstream IL-33-ST2 signalling during mucus fluctuations. Kazachstania pintolopesii-induced type 2 immunity enhanced resistance to helminth infections or aggravated gastrointestinal allergy in a context-dependent manner. Our findings indicate that K. pintolopesii is a mouse commensal and serves as a valuable model organism for studying gut fungal commensalism and immunity in its native host. Its unnoticed presence in mouse facilities highlights the need to evaluate its influence on experimental outcomes and phenotypes.

Gut-liver axis: Recent concepts in pathophysiology in alcohol-associated liver disease

The growing recognition of the role of the gut microbiome's impact on alcohol-associated diseases, especially in alcohol-associated liver disease, emphasizes the need to understand molecular mechanisms involved in governing organ-organ communication to identify novel avenues to combat alcohol-associated diseases. The gut-liver axis refers to the bidirectional communication and interaction between the gut and the liver. Intestinal microbiota plays a pivotal role in maintaining homeostasis within the gut-liver axis, and this axis plays a significant role in alcohol-associated liver disease. The intricate communication between intestine and liver involves communication between multiple cellular components in each organ that enable them to carry out their physiological functions. In this review, we focus on novel approaches to understanding how chronic alcohol exposure impacts the microbiome and individual cells within the liver and intestine, as well as the impact of ethanol on the molecular machinery required for intraorgan and interorgan communication.

Gut Bacteria in Alcohol-Associated Liver Disease

Alcohol-associated liver disease (ALD) poses a significant global public health challenge, with high patient mortality rates and economic burden. The gut microbiome plays an important role in the onset and progression of alcohol-associated liver disease. Excessive alcohol consumption disrupts the intestinal barrier, facilitating the entry of harmful microbes and their products into the liver, exacerbating liver damage. Dysbiosis, marked by imbalance in gut bacteria, correlates with ALD severity. Promising microbiota-centered therapies include probiotics, phages, and fecal microbiota transplantation. Clinical trials demonstrate the potential of these interventions to improve liver function and patient outcomes, offering a new frontier in ALD treatment.

Effects of forages on the microbiota of crossed sheep on cold Plateau

Diet is an important component to influence microbiota, there are less data available about the microbiome of Suffolk cross with Tibetan (SCT) animals with different fodders. The current study was conducted for comparing the fungi microbiota in SCT sheep fed with different forages. Sequencing of ileum samples from sheep groups of AH (alfalfa and oat grass), BH (mixture of grass and concentrated feeds), CH (concentrated feed I), DH (concentrated feed II) and EH (concentrated feed III) achieved 3,171,271 raw and 2,719,649 filtered sequences. Concentrated feeds changed fungi microbiota in SCT sheep with three phyla and 47 genera significantly different among the groups. Genera include positive genus of Scytalidium and negative fungi of Sarocladium, Kazachstania, Gibberella, Scytalidium, Candida, Wickerhamomyces. The findings of our study will contribute to efficient feeding of SCT sheep at cold plateau areas.

Cell-to-cell and organ-to-organ crosstalk in the pathogenesis of alcohol-associated liver disease

Alcohol-associated liver disease (ALD) is a growing global health concern and its prevalence and severity are increasing steadily. While bacterial endotoxin translocation into the portal circulation is a well-established key factor, recent evidence highlights the critical role of sterile inflammation, triggered by diverse stimuli, in alcohol-induced liver injury. This review provides a comprehensive analysis of the complex interactions within the hepatic microenvironment in ALD. It examines the contributions of both parenchymal cells, like hepatocytes, and non-parenchymal cells, such as hepatic stellate cells, Kupffer cells, neutrophils, and liver sinusoidal endothelial cells, in driving the progression of the disease. Additionally, we explored the involvement of key mediators, including cytokines, chemokines and inflammasomes, which regulate inflammatory responses and promote liver injury and fibrosis. A particular focus has been placed on extracellular vesicles (EVs) as essential mediators of intercellular communication both within and beyond the liver. These vesicles facilitate the transfer of signalling molecules, such as microRNAs and proteins, which modulate immune responses, fibrogenesis and lipid metabolism, thereby influencing disease progression. Moreover, we underscore the importance of organ-to-organ crosstalk, particularly in the gut-liver axis, where dysbiosis and increased intestinal permeability lead to microbial translocation, exacerbating hepatic inflammation. The adipose-liver axis is also highlighted, particularly the impact of adipokines and free fatty acids from adipose tissue on hepatic steatosis and inflammation in the context of alcohol consumption.

Gut mycobiome alterations and implications for liver diseases

Chronic liver disease and its complications are a significant global health burden. Changes in fungal communities (mycobiome), an integral component of the gut microbiome, are associated with and contribute to the development of liver disease. Fungal dysbiosis can induce intestinal barrier dysfunction and allow fungal products to translocate to the liver causing progression of disease. This review explores recent progress in understanding the compositional and functional diversity of gut mycobiome signatures across different liver diseases. It delves into causative connections between gut fungi and liver diseases. We emphasize the significance of fungal translocation, with a particular focus on fungal-derived metabolites and immune cells induced by fungi, as key contributors to liver disease. Furthermore, we review the potential impact of the intrahepatic mycobiome on the progression of liver diseases.

The gut microbiome in alcohol use disorder and alcohol-associated liver disease: A systematic review of clinical studies

Evidence suggests that a relationship exists between the gut microbiome and the pathogenesis of alcohol use disorder (AUD) and alcohol-associated liver disease (AALD). This systematic review identified studies that investigated the gut microbiome in individuals with an AUD or an AALD. A search was conducted on October 27, 2022, in PubMed, Web of Science, and Embase databases. Fifty studies satisfied eligibility criteria. Most studies found evidence for gut dysbiosis in individuals with AUD and AALD. Microbiome intervention studies have mostly been conducted in AALD patients; fecal microbial transplant interventions show the most promise. Because most studies were conducted cross-sectionally, the causal relationship between the gut microbiome and alcohol use is unknown. Furthermore, almost all studies have been conducted in predominantly male populations, leaving critical questions regarding sex differences and generalizability of the findings. The study summaries and recommendations provided in this review seek to identify areas for further research and to highlight potential gut microbial interventions for treating AUD and AALD.

Dangers of the chronic stress response in the context of the microbiota-gut-immune-brain axis and mental health: a narrative review

More than 20% of American adults live with a mental disorder, many of whom are treatment resistant or continue to experience symptoms. Other approaches are needed to improve mental health care, including prevention. The role of the microbiome has emerged as a central tenet in mental and physical health and their interconnectedness (well-being). Under normal conditions, a healthy microbiome promotes homeostasis within the host by maintaining intestinal and brain barrier integrity, thereby facilitating host well-being. Owing to the multidirectional crosstalk between the microbiome and neuro-endocrine-immune systems, dysbiosis within the microbiome is a main driver of immune-mediated systemic and neural inflammation that can promote disease progression and is detrimental to well-being broadly and mental health in particular. In predisposed individuals, immune dysregulation can shift to autoimmunity, especially in the presence of physical or psychological triggers. The chronic stress response involves the immune system, which is intimately involved with the gut microbiome, particularly in the process of immune education. This interconnection forms the microbiota-gut-immune-brain axis and promotes mental health or disorders. In this brief review, we aim to highlight the relationships between stress, mental health, and the gut microbiome, along with the ways in which dysbiosis and a dysregulated immune system can shift to an autoimmune response with concomitant neuropsychological consequences in the context of the microbiota-gut-immune-brain axis. Finally, we aim to review evidenced-based prevention strategies and potential therapeutic targets.

Gut microbiome in alcohol use disorder: Implications for health outcomes and therapeutic strategies-a literature review

Alcohol use disorder (AUD) represents a major public health issue which affects millions of people globally and consist a chronic relapsing condition associated with substantial morbidity and mortality. The gut microbiome plays a crucial role in maintaining overall health and has emerged as a significant contributor to the pathophysiology of various psychiatric disorders. Recent evidence suggests that the gut microbiome is intimately linked to the development and progression of AUD, with alcohol consumption directly impacting its composition and function. This review article aims to explore the intricate relationship between the gut microbiome and AUD, focusing on the implications for mental health outcomes and potential therapeutic strategies. We discuss the bidirectional communication between the gut microbiome and the brain, highlighting the role of microbiota-derived metabolites in neuroinflammation, neurotransmission, and mood regulation. Furthermore, we examine the influence of AUD-related factors, such as alcohol-induced gut dysbiosis and increased intestinal permeability, on mental health outcomes. Finally, we explore emerging therapeutic avenues targeting the gut microbiome in the management of AUD, including prebiotics, probiotics, and fecal microbiota transplantation. Understanding the complex interplay between the gut microbiome and AUD holds promise for developing novel interventions that could improve mental health outcomes in individuals with AUD.

Alcohol-induced gut microbiome dysbiosis enhances the colonization of Klebsiella pneumoniae on the mouse intestinal tract

Chronic alcohol consumption, an important risk factor for diseases and deaths, can cause intestinal microbiota dysbiosis and increase the infection of some opportunistic pathogens. However, the current studies on the effects of alcohol-induced intestinal microbiota dysbiosis on gut colonization of Klebsiella pneumoniae are still scarce. In the present study, we established a binge-on-chronic alcohol model in mice to identify the characteristics of alcohol-induced intestinal microbiome and metabolite dysbiosis using multi-omics and explored the effects and potential mechanisms of these dysbioses on the intestinal colonization of K. pneumoniae. The results show that chronic alcohol consumption alters the diversity and composition of gut microbiota (including bacteria and fungi), decreases the complexity of the interaction between intestinal bacteria and fungi, disturbs the gut metabolites, and promotes the colonization of K. pneumoniae on the gut of mice. The relevance analyses find that alcohol-induced gut microbiome dysbiosis has a strong correlation with the alteration of secondary bile acids. In vitro results suggest that the high concentration of lithocholic acid, a secondary bile acid, could significantly inhibit the proliferation of K. pneumoniae, and the adhesion of K. pneumoniae to Caco-2 cells. Our results indicate that alcohol-induced microbiome dysbiosis contributes to decreased levels of secondary bile acids, which was one of the main reasons affecting the colonization of K. pneumoniae in mice's intestines. Some secondary bile acids (e.g., lithocholic acid) might be a potential drug to prevent the colonization and spread of K. pneumoniae.IMPORTANCEAlcohol is one of the most commonly misused substances in our lives. However, long-term heavy drinking will increase the colonization of some opportunistic pathogens (e.g., Klebsiella pneumoniae) in the body. Here, we revealed that binge-on-chronic alcohol consumption disrupted the balance between gut bacteria and fungi, induced the gut microbiome and metabolites dysbiosis, and promoted the colonization of K. pneumoniae in the intestine of mice. In particular, alcohol-taking disrupted intestinal bile acid metabolism and reduced the lithocholic acid concentration. However, a high concentration of lithocholic acid can protect against intestinal colonization of K. pneumoniae by inhabiting the bacterial growth and adhesion to the host cell. Hence, regulating the balance of gut microbiota and intestinal bile acid metabolism may be a potential strategy for reducing the risk of K. pneumoniae infection and spread.

Selection of ethanol tolerant strains of Candida albicans by repeated ethanol exposure results in strains with reduced susceptibility to fluconazole

Candida albicans is a commensal yeast that has important impacts on host metabolism and immune function, and can establish life-threatening infections in immunocompromised individuals. Previously, C. albicans colonization has been shown to contribute to the progression and severity of alcoholic liver disease. However, relatively little is known about how C. albicans responds to changing environmental conditions in the GI tract of individuals with alcohol use disorder, namely repeated exposure to ethanol. In this study, we repeatedly exposed C. albicans to high concentrations (10% vol/vol) of ethanol-a concentration that can be observed in the upper GI tract of humans following consumption of alcohol. Following this repeated exposure protocol, ethanol small colony (Esc) variants of C. albicans isolated from these populations exhibited increased ethanol tolerance, altered transcriptional responses to ethanol, and cross-resistance/tolerance to the frontline antifungal fluconazole. These Esc strains exhibited chromosomal copy number variations and carried polymorphisms in genes previously associated with the acquisition of fluconazole resistance during human infection. This study identifies a selective pressure that can result in evolution of fluconazole tolerance and resistance without previous exposure to the drug.

Fungal signature differentiates alcohol-associated liver disease from nonalcoholic fatty liver disease

The fungal microbiota plays an important role in the pathogenesis of alcohol-associated liver disease (ALD) and nonalcoholic fatty liver disease (NAFLD). In this study, we aimed to compare changes of the fecal fungal microbiota between patients with ALD and NAFLD and to elucidate patterns in different disease stages between the two conditions. We analyzed fungal internal transcribed spacer 2 (ITS2) sequencing using fecal samples from a cohort of 48 patients with ALD, 78 patients with NAFLD, and 34 controls. The fungal microbiota differed significantly between ALD and NAFLD. The genera Saccharomyces, Kluyveromyces, Scopulariopsis, and the species Candida albicans (C. albicans), Malassezia restricta (M. restricta), Scopulariopsis cordiae (S. cordiae) were significantly increased in patients with ALD, whereas the genera Kazachstania and Mucor were significantly increased in the NAFLD cohort. We identified the fungal signature consisting of Scopulariopsis, Kluyveromyces, M. restricta, and Mucor to have the highest discriminative ability to detect ALD vs NAFLD with an area under the curve (AUC) of 0.93. When stratifying the ALD and NAFLD cohorts by fibrosis severity, the fungal signature with the highest AUC of 0.92 to distinguish ALD F0-F1 vs NAFLD F0-F1 comprised Scopulariopsis, Kluyveromyces, Mucor, M. restricta, and Kazachstania. For more advanced fibrosis stages (F2-F4), the fungal signature composed of Scopulariopsis, Kluyveromyces, Mucor, and M. restricta achieved the highest AUC of 0.99 to differentiate ALD from NAFLD. This is the first study to identify a fungal signature to differentiate two metabolic fatty liver diseases from each other, specifically ALD from NAFLD. This might have clinical utility in unclear cases and might hence help shape treatment approaches. However, larger studies are required to validate this fungal signature in other populations of ALD and NAFLD.

The mycobiome as integral part of the gut microbiome: crucial role of symbiotic fungi in health and disease

The gut mycobiome significantly affects host health and immunity. However, most studies have focused on symbiotic bacteria in the gut microbiome, whereas less attention has been given to symbiotic fungi. Although fungi constitute only 0.01%-0.1% of the gut microbiome, their larger size and unique immunoregulatory functions make them significant. Factors like diet, antimicrobials use, and age can disrupt the fungal community, leading to dysbiosis. Fungal-bacterial-host immune interactions are critical in maintaining gut homeostasis, with fungi playing a role in mediating immune responses such as Th17 cell activation. This review highlights methods for studying gut fungi, the composition and influencing factors of the gut mycobiome, and its potential in therapeutic interventions for intestinal and hepatic diseases. We aim to provide new insights into the underexplored role of gut fungi in human health.

Intestinal microbiome dysbiosis in alcohol-dependent patients and its effect on rat behaviors

IMPORTANCE

Intestinal microbiome dysbiosis is associated with psychiatric disease through the "microbiota-gut-brain" axis. Here, we revealed that there was obvious intestinal microbiome (including bacterial and fungal) dysbiosis in alcohol-dependent patients. Alcohol consumption seriously disturbs the gut equilibrium between bacteria and fungi, reduces the interactions among bacterial-fungal trans-kingdom, and increases intestinal permeability. Gut microbiota should be considered as a whole to study the development of alcohol dependence. The gut microbiome of alcohol-dependent patients increased the anxiety- and depression-like behavior in rats. The gut microbiota dysbiosis may promote the development of alcohol dependence by regulating the endogenous cholecystokinin (CCK) and related receptors. Hence, regulating the balance of gut microbiota and the endogenous CCK may be a potential strategy for reducing the risk of relapse in alcohol addiction patients.

The Protective Effect of Auricularia cornea var. Li. Polysaccharide on Alcoholic Liver Disease and Its Effect on Intestinal Microbiota

This study's objective was to examine the protective effect and mechanism of a novel polysaccharide (AYP) from Auricularia cornea var. Li. on alcoholic liver disease in mice. AYP was extracted from the fruiting bodies of Auricularia cornea var. Li. by enzymatic extraction and purified by DEAE-52 and Sephacryl S-400. Structural features were determined using high-performance liquid chromatography, ion exchange chromatography and Fourier-transform infrared analysis. Additionally, alcoholic liver disease (ALD) mice were established to explore the hepatoprotective activity of AYP (50, 100 and 200 mg/kg/d). Here, our results showed that AYP presented high purity with a molecular weight of 4.64 × 105 Da. AYP was composed of galacturonic acid, galactose, glucose, arabinose, mannose, xylose, rhamnose, ribos, glucuronic acid and fucose (molar ratio: 39.5:32.9:23.6:18.3:6.5:5.8:5.8:3.3:2:1.1). Notably, AYP remarkably reduced liver function impairment (alanine aminotransferase (ALT), aspartate aminotransferase (AST), triglyceride (TG), total cholesterol (TC)), nitric oxide (NO) and malondialdehyde (MDA) of the liver and enhanced the activity of antioxidant enzymes (superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and glutathione (gGSH)) in mice with ALD. Meanwhile, the serum level of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-1β (IL-1β) were reduced in ALD mice treated by AYP. Furthermore, the AYPH group was the most effective and was therefore chosen to further investigate its effect on the intestinal microbiota (bacteria and fungi) of ALD mice. Based on 16s rRNA and ITS-1 sequencing data, AYP influenced the homeostasis of intestinal microbiota to mitigate the damage of ALD mice, possibly by raising the abundance of favorable microbiota (Muribaculaceae, Lachnospiraceae and Kazachstania) and diminishing the abundance of detrimental microbiota (Lactobacillus, Mortierella and Candida). This discovery opens new possibilities for investigating physiological activity in A. cornea var. Li. and provides theoretical references for natural liver-protecting medication research.

Selection of Ethanol Tolerant Strains of Candida albicans by Repeated Ethanol Exposure Results in Strains with Reduced Susceptibility to Fluconazole

Candida albicans is a commensal yeast that has important impacts on host metabolism and immune function, and can establish life-threatening infections in immunocompromised individuals. Previously, C. albicans colonization has been shown to contribute to the progression and severity of alcoholic liver disease. However, relatively little is known about how C. albicans responds to changing environmental conditions in the GI tract of individuals with alcohol use disorder, namely repeated exposure to ethanol. In this study, we repeatedly exposed C. albicans to high concentrations (10% vol/vol) of ethanol-a concentration that can be observed in the upper GI tract of humans following consumption of alcohol. Following this repeated exposure protocol, ethanol small colony (Esc) variants of C. albicans isolated from these populations exhibited increased ethanol tolerance, altered transcriptional responses to ethanol, and cross-resistance/tolerance to the frontline antifungal fluconazole. These Esc strains exhibited chromosomal copy number variations and carried polymorphisms in genes previously associated with the acquisition of fluconazole resistance during human infection. This study identifies a selective pressure that can result in evolution of fluconazole tolerance and resistance without previous exposure to the drug.

Alcohol-Associated Liver Disease: Evolving Concepts and Treatments

Alcohol is a prominent cause of liver disease worldwide with higher prevalence in developed nations. The spectrum of alcohol-associated liver disease (ALD) encompasses a diverse range of clinical entities, from asymptomatic isolated steatosis to decompensated cirrhosis, and in some cases, acute or chronic liver failure. Consequently, it is important for healthcare practitioners to maintain awareness and systematically screen for ALD. The optimal evaluation and management of ALD necessitates a collaborative approach, incorporating a multidisciplinary team and accounting for concurrent medical conditions. A repertoire of therapeutic interventions exists to support patients in achieving alcohol cessation and sustaining remission, with complete abstinence being the ultimate objective. This review explores the existing therapeutic options for ALD acknowledging geographical discrepancies in accessibility. Recent innovations, including the inclusion of alcohol consumption biomarkers into clinical protocols and the expansion of liver transplantation eligibility to encompass severe alcohol-associated hepatitis, are explored.

Fecal cytolysin does not predict disease severity in acutely decompensated cirrhosis and acute-on-chronic liver failure

BACKGROUND

Cirrhosis with acute decompensation (AD) and acute-on-chronic liver failure (ACLF) are characterized by high morbidity and mortality. Cytolysin, a toxin from Enterococcus faecalis (E. faecalis), is associated with mortality in alcohol-associated hepatitis (AH). It is unclear whether cytolysin also contributes to disease severity in AD and ACLF.

METHODS

We studied the role of fecal cytolysin in 78 cirrhotic patients with AD/ACLF. Bacterial DNA from fecal samples was extracted and real-time quantitative polymerase chain reaction (PCR) was performed. The association between fecal cytolysin and liver disease severity in cirrhosis with AD or ACLF was analyzed.

RESULTS

Fecal cytolysin and E. faecalis abundance did not predict chronic liver failure (CLIF-C) AD and ACLF scores. Presence of fecal cytolysin was not associated with other liver disease markers, including Fibrosis-4 (FIB-4) index, 'Age, serum Bilirubin, INR, and serum Creatinine (ABIC)' score, Child-Pugh score, model for end-stage liver disease (MELD) nor MELD-Na scores in AD or ACLF patients.

CONCLUSIONS

Fecal cytolysin does not predict disease severity in AD and ACLF patients. The predictive value of fecal cytolysin positivity for mortality appears to be restricted to AH.

Stress mechanism involved in the progression of alcoholic liver disease and the therapeutic efficacy of nanoparticles

Alcoholic liver disease (ALD) poses a significant threat to human health, with excessive alcohol intake disrupting the immunotolerant environment of the liver and initiating a cascade of pathological events. This progressive disease unfolds through fat deposition, proinflammatory cytokine upregulation, activation of hepatic stellate cells, and eventual development of end-stage liver disease, known as hepatocellular carcinoma (HCC). ALD is intricately intertwined with stress mechanisms such as oxidative stress mediated by reactive oxygen species, endoplasmic reticulum stress, and alcohol-induced gut dysbiosis, culminating in increased inflammation. While the initial stages of ALD can be reversible with diligent care and abstinence, further progression necessitates alternative treatment approaches. Herbal medicines have shown promise, albeit limited by their poor water solubility and subsequent lack of extensive exploration. Consequently, researchers have embarked on a quest to overcome these challenges by delving into the potential of nanoparticle-mediated therapy. Nanoparticle-based treatments are being explored for liver diseases that share similar mechanisms with alcoholic liver disease. It underscores the potential of these innovative approaches to counteract the complex pathogenesis of ALD, providing new avenues for therapeutic intervention. Nevertheless, further investigations are imperative to fully unravel the therapeutic potential and unlock the promise of nanoparticle-mediated therapy specifically tailored for ALD treatment.

Stress mechanism involved in the progression of alcoholic liver disease and the therapeutic efficacy of nanoparticles

Alcoholic liver disease (ALD) poses a significant threat to human health, with excessive alcohol intake disrupting the immunotolerant environment of the liver and initiating a cascade of pathological events. This progressive disease unfolds through fat deposition, proinflammatory cytokine upregulation, activation of hepatic stellate cells, and eventual development of end-stage liver disease, known as hepatocellular carcinoma (HCC). ALD is intricately intertwined with stress mechanisms such as oxidative stress mediated by reactive oxygen species, endoplasmic reticulum stress, and alcohol-induced gut dysbiosis, culminating in increased inflammation. While the initial stages of ALD can be reversible with diligent care and abstinence, further progression necessitates alternative treatment approaches. Herbal medicines have shown promise, albeit limited by their poor water solubility and subsequent lack of extensive exploration. Consequently, researchers have embarked on a quest to overcome these challenges by delving into the potential of nanoparticle-mediated therapy. Nanoparticle-based treatments are being explored for liver diseases that share similar mechanisms with alcoholic liver disease. It underscores the potential of these innovative approaches to counteract the complex pathogenesis of ALD, providing new avenues for therapeutic intervention. Nevertheless, further investigations are imperative to fully unravel the therapeutic potential and unlock the promise of nanoparticle-mediated therapy specifically tailored for ALD treatment.

Pathogenesis of Alcoholic Fatty Liver a Narrative Review

Alcohol effect hepatic lipid metabolism through various mechanisms, leading synergistically to an accumulation of fatty acids (FA) and triglycerides. Obesity, as well as dietary fat (saturated fatty acids (FA) versus poly-unsaturated fatty acids (PUFA)) may modulate the hepatic fat. Alcohol inhibits adenosine monophosphate activated kinase (AMPK). AMPK activates peroxisome proliferator activated receptor a (PPARα) and leads to a decreased activation of sterol regulatory element binding protein 1c (SRABP1c). The inhibition of AMPK, and thus of PPARα, results in an inhibition of FA oxidation. This ß-oxidation is further reduced due to mitochondrial damage induced through cytochrome P4502E1 (CYP2E1)-driven oxidative stress. Furthermore, the synthesis of FAs is stimulated through an activation of SHREP1. In addition, alcohol consumption leads to a reduced production of adiponectin in adipocytes due to oxidative stress and to an increased mobilization of FAs from adipose tissue and from the gut as chylomicrons. On the other side, the secretion of FAs via very-low-density lipoproteins (VLDL) from the liver is inhibited by alcohol. Alcohol also affects signal pathways such as early growth response 1 (Egr-1) associated with the expression of tumour necrosis factor α (TNF α), and the mammalian target of rapamycin (mTOR) a key regulator of autophagy. Both have influence the pathogenesis of alcoholic fatty liver. Alcohol-induced gut dysbiosis contributes to the severity of ALD by increasing the metabolism of ethanol in the gut and promoting intestinal dysfunction. Moreover, pathogen-associated molecular patterns (PAMPS) via specific Toll-like receptor (TLR) bacterial overgrowth leads to the translocation of bacteria. Endotoxins and toxic ethanol metabolites enter the enterohepatic circulation, reaching the liver and inducing the activation of the nuclear factor kappa-B (NFκB) pathway. Pro-inflammatory cytokines released in the process contribute to inflammation and fibrosis. In addition, cellular apoptosis is inhibited in favour of necrosis.

IgY antibodies against cytolysin reduce ethanol-induced liver disease in mice

BACKGROUND AND AIMS

Patients with severe alcohol-associated hepatitis have high morbidity and mortality. Novel therapeutic approaches are urgently needed. The aims of our study were to confirm the predictive value of cytolysin-positive Enterococcus faecalis ( E. faecalis ) for mortality in patients with alcohol-associated hepatitis and to assess the protective effect of specific chicken immunoglobulin Y (IgY) antibodies against cytolysin in vitro and in a microbiota-humanized mouse model of ethanol-induced liver disease.

APPROACH AND RESULTS

We investigated a multicenter cohort of 26 subjects with alcohol-associated hepatitis and confirmed our previous findings that the presence of fecal cytolysin-positive E. faecalis predicted 180-day mortality in those patients. After combining this smaller cohort with our previously published multicenter cohort, the presence of fecal cytolysin has a better diagnostic area under the curve, better other accuracy measures, and a higher odds ratio to predict death in patients with alcohol-associated hepatitis than other commonly used liver disease models. In a precision medicine approach, we generated IgY antibodies against cytolysin from hyperimmunized chickens. Neutralizing IgY antibodies against cytolysin reduced cytolysin-induced cell death in primary mouse hepatocytes. The oral administration of IgY antibodies against cytolysin decreased ethanol-induced liver disease in gnotobiotic mice colonized with stool from cytolysin-positive patients with alcohol-associated hepatitis.

CONCLUSIONS

E. faecalis cytolysin is an important mortality predictor in alcohol-associated hepatitis patients, and its targeted neutralization through specific antibodies improves ethanol-induced liver disease in microbiota-humanized mice.

Probiotics, prebiotics, and synbiotics in nonalcoholic fatty liver disease and alcohol-associated liver disease

The use of probiotics, prebiotics, and synbiotics has become an important therapy in numerous gastrointestinal diseases in recent years. Modifying the gut microbiota, this therapeutic approach helps to restore a healthy microbiome. Nonalcoholic fatty liver disease and alcohol-associated liver disease are among the leading causes of chronic liver disease worldwide. A disrupted intestinal barrier, microbial translocation, and an altered gut microbiome metabolism, or metabolome, are crucial in the pathogenesis of these chronic liver diseases. As pro-, pre-, and synbiotics modulate these targets, they were identified as possible new treatment options for liver disease. In this review, we highlight the current findings on clinical and mechanistic effects of this therapeutic approach in nonalcoholic fatty liver disease and alcohol-associated liver disease.

Any alcohol use in NAFLD patients is associated with significant changes to the intestinal virome

BACKGROUND AND AIMS

The prevalence of alcohol use disorder (AUD) and metabolic dysfunction-associated fatty liver disease (MAFLD) are increasing worldwide, leading to the increasing likelihood of both etiologies contributing to a patient's liver disease. However, the effects of modest alcohol use in NAFLD are controversial and more studies are needed. We compared the intestinal viromes of patients with AUD and NAFLD in order to evaluate the effect of alcohol consumption on the intestinal viromes of NAFLD patients by extracting virus-like particles and performing metagenomic sequencing.

APPROACH AND RESULTS

Viral nucleic acids were extracted from fecal samples and subjected to metagenomic sequencing. We demonstrate significant differences in the intestinal viromes of NAFLD and AUD patients, and that alcohol use in NAFLD patients reclassified to MAFLD accounted for significant differences in the intestinal viromes. The relative abundance of several Lactococcus phages was more similar between AUD patients and alcohol-consuming MAFLD patients than non-alcohol-consuming MAFLD patients and control subjects, and multivariate modeling using the most discriminating Lactococcus phages could better predict alcohol use in the MAFLD population than the alcohol-associated liver disease/NAFLD Index. Significant differences in the viral composition and diversity were also seen between MAFLD patients with low and moderate alcohol consumption compared with no alcohol consumption.

CONCLUSIONS

The intestinal virome of MAFLD patients who consume low to moderate amounts of alcohol are significantly different from those who do not, and many features of the intestinal virome of alcohol-consuming MAFLD patients resemble that of AUD patients.

Noninvasive biomarkers in pediatric nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease worldwide among children and adolescents. It encompasses a spectrum of disease, from its mildest form of isolated steatosis, to nonalcoholic steatohepatitis (NASH) to liver fibrosis and cirrhosis, or end-stage liver disease. The early diagnosis of pediatric NAFLD is crucial in preventing disease progression and in improving outcomes. Currently, liver biopsy is the gold standard for diagnosing NAFLD. However, given its invasive nature, there has been significant interest in developing noninvasive methods that can be used as accurate alternatives. Here, we review noninvasive biomarkers in pediatric NAFLD, focusing primarily on the diagnostic accuracy of various biomarkers as measured by their area under the receiver operating characteristic, sensitivity, and specificity. We examine two major approaches to noninvasive biomarkers in children with NAFLD. First, the biological approach that quantifies serological biomarkers. This includes the study of individual circulating molecules as biomarkers as well as the use of composite algorithms derived from combinations of biomarkers. The second is a more physical approach that examines data measured through imaging techniques as noninvasive biomarkers for pediatric NAFLD. Each of these approaches was applied to children with NAFLD, NASH, and NAFLD with fibrosis. Finally, we suggest possible areas for future research based on current gaps in knowledge.

Phage therapy in gut microbiome

Phage therapy, the use of bacteriophage viruses for bacterial infection treatment, has been around for almost a century, but with the increase in antibiotic use, its importance has declined rapidly. There has been renewed interest in revisiting this practice due to the general decline in the effectiveness of antibiotics, combined with improved understanding of human microbiota and advances in sequencing technologies. Phage therapy has been proposed as a clinical alternative to restore the gut microbiota in the absence of an effective treatment. That is due to its immunomodulatory and bactericidal effects against its target bacteria. In the gastrointestinal diseases field, phage therapy has been studied mainly as a promising tool in infectious diseases treatment, such as cholera and diarrhea. However, many studies have been conducted in non-communicable diseases, such as the targeting of adherent invasive Escherichia coli in Crohn's disease, the treatment of Clostridioides difficile in ulcerative colitis, the eradication of Fusobacterium nucleatum in colorectal cancer, the targeting of alcohol-producing Klebsiella pneumoniae in non-alcoholic fatty liver disease, or Enterococcus faecalis in alcohol-associated hepatitis. This review will summarize the changes in the gut microbiota and the phageome in association with some gastrointestinal and liver diseases and highlight the recent scientific advances in phage therapy as a therapeutic tool for their treatment.

Fungal infections and the fungal microbiome in hepatobiliary disorders

Liver and biliary diseases affect more than a billion people worldwide, with high associated morbidity and mortality. The impact of the intestinal bacterial microbiome on liver diseases has been well established. However, the fungal microbiome, or mycobiome, has been overlooked for a long time. Recently, several studies have shed light on the role of the mycobiome in the development and progression of hepatobiliary diseases. In particular, the fungal genus Candida has been found to be involved in the pathogenesis of multiple hepatobiliary conditions. Herein, we compare colonisation and infection, describe mycobiome findings in the healthy state and across the various hepatobiliary conditions, and point toward communalities. We detail how quantitation of immune responses to fungal antigens can be employed to predict disease severity, e.g. using antibodies to Saccharomyces cerevisiae or specific anti-Candida albicans antibodies. We also show how fungal products (e.g. beta-glucans, candidalysin) activate the host's immune system to exacerbate liver and biliary diseases. Finally, we describe how the gut mycobiome can be modulated to ameliorate hepatobiliary conditions.

Candida albicans-specific Th17 cell-mediated response contributes to alcohol-associated liver disease

Alcohol-associated liver disease is accompanied by intestinal mycobiome dysbiosis, yet the impacts on liver disease are unclear. We demonstrate that Candida albicans-specific T helper 17 (Th17) cells are increased in circulation and present in the liver of patients with alcohol-associated liver disease. Chronic ethanol administration in mice causes migration of Candida albicans (C. albicans)-reactive Th17 cells from the intestine to the liver. The antifungal agent nystatin decreased C. albicans-specific Th17 cells in the liver and reduced ethanol-induced liver disease in mice. Transgenic mice expressing T cell receptors (TCRs) reactive to Candida antigens developed more severe ethanol-induced liver disease than transgene-negative littermates. Adoptively transferring Candida-specific TCR transgenic T cells or polyclonal C. albicans-primed T cells exacerbated ethanol-induced liver disease in wild-type mice. Interleukin-17 (IL-17) receptor A signaling in Kupffer cells was required for the effects of polyclonal C. albicans-primed T cells. Our findings indicate that ethanol increases C. albicans-specific Th17 cells, which contribute to alcohol-associated liver disease.

Malassezia restricta promotes alcohol-induced liver injury

Chronic alcohol consumption is associated with intestinal fungal dysbiosis, yet we understand little about how alterations of intestinal fungi (mycobiota) contribute to the pathogenesis of alcohol-associated liver disease. By reanalyzing internal transcribed spacer 2 amplicon sequencing of fecal samples from a cohort of 66 patients with alcohol use disorder for presence (as opposed to relative abundance) of fungal species, we observed that the presence of Malassezia restricta was associated with increased markers of liver injury. M. restricta exacerbates ethanol-induced liver injury both in acute binge and chronic ethanol-feeding models in mice. Using bone marrow chimeric mice, we found that the disease exacerbating effect by M. restricta was mediated by C-type lectin domain family 4, member N on bone marrow-derived cells. M. restricta induces inflammatory cytokines and chemokines in Kupffer cells through C-type lectin domain family 4, member N signaling. Targeting fungal pathobionts might be a therapeutic strategy for alcohol-associated liver disease.

The emerging role of the gut mycobiome in liver diseases

In recent years, it has become clear that gut microbiota plays a major role in the human body, both in health and disease. Because of that, the gut microbiome and its impact on human well-being are getting wider and wider attention. Studies focused on the liver are not an exception. However, the majority of the analyses are concentrated on the bacterial part of the gut microbiota, while the fungi living in the human intestines are often omitted or underappreciated. This review is focused on the gut mycobiome as an important factor that should be taken into consideration regarding liver homeostasis and its perturbations. We have collected the findings in this field and we discuss their importance. We aim to emphasize the fungal compositional changes related to liver diseases and, by that, provide novel insights into the directions of liver research and gut microbiota as a therapeutic target for liver diseases.

A critical review of recent knowledge of alcohol's effects on the immunological response in different tissues

Alcohol misuse contributes to the dysregulation of immune responses and multiorgan dysfunction across various tissues, which are associated with higher risk of morbidity and mortality in people with alcohol use disorders. Organ-specific immune cells, including microglia in the brain, alveolar macrophages in the lungs, and Kupffer cells in the liver, play vital functions in host immune defense through tissue repair and maintenance of homeostasis. However, binge drinking and chronic alcohol misuse impair these immune cells' abilities to regulate inflammatory signaling and metabolism, thus contributing to multiorgan dysfunction. Further complicating these delicate systems, immune cell dysfunction associated with alcohol misuse is exacerbated by aging and gut barrier leakage. This critical review describes recent advances in elucidating the potential mechanisms by which alcohol misuse leads to derangements in host immunity and highlights current gaps in knowledge that may be the focus of future investigations.

Pathogenesis of Alcohol-Associated Liver Disease

Excessive alcohol consumption is a global healthcare problem with enormous social, economic, and clinical consequences. While chronic, heavy alcohol consumption causes structural damage and/or disrupts normal organ function in virtually every tissue of the body, the liver sustains the greatest damage. This is primarily because the liver is the first to see alcohol absorbed from the gastrointestinal tract via the portal circulation and second, because the liver is the principal site of ethanol metabolism. Alcohol-induced damage remains one of the most prevalent disorders of the liver and a leading cause of death or transplantation from liver disease. Despite extensive research on the pathophysiology of this disease, there are still no targeted therapies available. Given the multifactorial mechanisms for alcohol-associated liver disease pathogenesis, it is conceivable that a multitherapeutic regimen is needed to treat different stages in the spectrum of this disease.

Inexpensive, Accurate, and Stable Method to Quantitate Blood Alanine Aminotransferase (ALT) Levels

Alanine aminotransferase (ALT) levels are frequently determined in serum and plasma samples and are a primary measure to quantitate hepatocellular injury in rodents, humans, and other organisms. An accurate, reliable, and scalable assay is hence of central importance. Here, we describe a methodology that fulfills those requirements, and demonstrates an excellent performance similar to a commercial ALT kit, with a long stable performance over several subsequent runs. Further, anticoagulation of blood samples with ethylenediaminetetraacetic acid (EDTA) or heparin results in similar ALT concentrations with this assay, whereas no anticoagulation significantly increases ALT levels. Mild hemolysis does not significantly increase ALT levels; however, moderate to severe hemolysis does lead to higher ALT levels. The assay provides stable results over a wide range of associated triglyceride concentrations that can be expected in serum and plasma samples from rodents and humans with dyslipidemia. It also performs well in diluted samples with a reduction of ALT levels corresponding to the factor used to dilute the samples. The described ALT reagent is also very affordable, costing less than 1/80 of comparable commercial kits. Based on the characteristics above, this methodology is suitable for a broad spectrum of applications in mice and possibly humans, where ALT concentrations need to be determined.

Cyclic Nucleotide Phosphodiesterases in Alcohol Use Disorders: Involving Gut Microbiota

Alcohol abuse is 1 of the most significant public health problems in the world. Chronic, excessive alcohol consumption not only causes alcohol use disorder (AUD) but also changes the gut and lung microbiota, including bacterial and nonbacterial types. Both types of microbiota can release toxins, further damaging the gastrointestinal and respiratory tracts; causing inflammation; and impairing the functions of the liver, lung, and brain, which in turn deteriorate AUD. Phosphodiesterases (PDEs) are critical in the control of intracellular cyclic nucleotides, including cyclic adenosine monophosphate and cyclic guanosine monophosphate. Inhibition of certain host PDEs reduces alcohol consumption and attenuates alcohol-related impairment. These PDEs are also expressed in the microbiota and may play a role in controlling microbiota-associated inflammation. Here, we summarize the influences of alcohol on gut/lung bacterial and nonbacterial microbiota as well as on the gut-liver/brain/lung axis. We then discuss the relationship between gut and lung microbiota-mediated PDE signaling and AUD consequences in addition to highlighting PDEs as potential targets for treatment of AUD.

Gut Microbiome and Alcohol-associated Liver Disease

Changes in gut microbiota (GM) may be associated with the causation and progression of multiple liver diseases such as metabolic-associated liver disease, alcohol-associated liver disease (ALD), alcohol-associated hepatitis (AH), primary biliary cholangitis, primary sclerosing cholangitis, autoimmune liver disease, and most importantly, complications of cirrhosis and portal hypertension such as hepatic encephalopathy (HE), infection, and hepatocellular carcinoma. ALD includes simple steatosis, steatohepatitis, AH, cirrhosis, and acute-on-chronic liver failure. Alcohol consumption is associated with GM changes even before ALD development, and continued alcohol intake results in progressive dysbiosis and development of clinical events such as AH, infection, and HE. The composition and function of GM, specific changes in bacterial communities, and the functional metabolism of GM are affected in the spectrum of ALD, as revealed using high-throughput sequencing. It was reported in preliminary studies that modulation of disrupted GM improves adverse clinical events and ameliorates disease progression in ALD. In this review, we exhaustively discuss the preclinical and clinical studies on GM in ALD and critically discuss GM modulation and its effects based on various human and animal models of ALD.

Intestinal virome in patients with alcohol use disorder and after abstinence

Alcohol use is a leading cause of chronic liver disease worldwide, and changes in the microbiome associated with alcohol use contribute to patients' risk for liver disease progression. Less is known about the effects of alcohol use on the intestinal viral microbiome (virome) and interactions between bacteriophages and their target bacteria. We studied changes in the intestinal virome of 62 clinically well-characterized patients with alcohol use disorder (AUD) during active alcohol use and after 2 weeks of alcohol abstinence, by extracting virus-like particles and performing metagenomic sequencing. We observed decreased abundance of Propionibacterium, Lactobacillus, and Leuconostoc phages in patients with active AUD when compared with controls, whereas after 2 weeks of alcohol abstinence, patients with AUD demonstrated an increase in the abundance of Propionibacterium, Lactobacillus, and Leuconostoc phages. The intestinal virome signature was also significantly different in patients with AUD with progressive liver disease, with increased abundance of phages targeting Enterobacteria and Lactococcus species phages compared with patients with AUD with nonprogressive liver disease. By performing moderation analyses, we found that progressive liver disease is associated with changes in interactions between some bacteriophages and their respective target bacteria. In summary, active alcohol use and alcohol-associated progressive liver disease are associated with changes in the fecal virome, some of which are partially reversible after a short period of abstinence. Progression of alcohol-associated liver disease is associated with changes in bacteriophage-bacteria interactions.

The Gut Microbiota: A Novel Player in Autoimmune Hepatitis

Autoimmune hepatitis (AIH) is a chronic immune-mediated liver disease distributed globally in all ethnicities with increasing prevalence. If left untreated, the disease will lead to cirrhosis, liver failure, or death. The intestinal microbiota is a complex ecosystem located in the human intestine, which extensively affects the human physiological and pathological processes. With more and more in-depth understandings of intestinal microbiota, a substantial body of studies have verified that the intestinal microbiota plays a crucial role in a variety of digestive system diseases, including alcohol-associated liver disease (ALD) and non-alcoholic fatty liver disease (NAFLD). However, only a few studies have paid attention to evaluate the relationship between AIH and the intestinal microbiota. While AIH pathogenesis is not fully elucidated yet, some studies have indicated that intestinal microbiota putatively made significant contributions to the occurrence and the development of AIH by triggering several specific signaling pathways, altering the metabolism of intestinal microbiota, as well as modulating the immune response in the intestine and liver. By collecting the latest related literatures, this review summarized the increasing trend of the aerobic bacteria abundance in both AIH patients and AIH mice models. Moreover, the combination of specific bacteria species was found distinct to AIH patients, which could be a promising tool for diagnosing AIH. In addition, there were alterations of luminal metabolites and immune responses, including decreased short-chain fatty acids (SCFAs), increased pathogen associated molecular patterns (PAMPs), imbalanced regulatory T (Treg)/Th17 cells, follicular regulatory T (TFR)/follicular helper T (TFH) cells, and activated natural killer T (NKT) cells. These alterations participate in the onset and the progression of AIH via multiple mechanisms. Therefore, some therapeutic methods based on restoration of intestinal microbiota composition, including probiotics and fecal microbiota transplantation (FMT), as well as targeted intestinal microbiota-associated signaling pathways, confer novel insights into the treatment for AIH patients.

Liver cirrhosis and immune dysfunction

Cirrhosis is end-stage liver disease resulting from various etiologies and is a common cause of death worldwide. The progression from compensated to decompensated cirrhosis to acute-on-chronic liver failure (ACLF) is due to multiple factors, including continuation of alcohol use or continued exposure to other toxins, an imbalance of the gut microbiota (dysbiosis), increased gut permeability and a disrupted immune response. This disrupted immune response is also named cirrhosis-associated immune dysfunction, which is characterized by worsening systemic inflammation with concomitant immune paralysis, as liver disease deteriorates. This review highlights central immunologic events during the exacerbation of cirrhosis and characterizes the different immune cell populations involved therein.

Illumina-Based Analysis Yields New Insights Into the Fungal Contamination Associated With the Processed Products of Crataegi Fructus

Crataegi Fructus, a medicinal and edible herb in China, has been considered a popular dietary supplement globally. It is used for the treatment of dyspepsia and chronic heart failure according to the Chinese Pharmacopoeia (2020). However, fungal contamination in Crataegi Fructus affects its quality and safety, thus preventing its global promotion. In this study, we comprehensively studied the fungal community in processed products of Crataegi Fructus by high-throughput sequencing. A total of 21 Crataegi Fructus samples were collected from five provinces in China, and the samples were divided into five groups based on collection areas, as well as into three groups based on processing methods. We then targeted the internal transcribed spacer 2 sequence through the Illumina Miseq PE300 platform to investigate fungal composition and diversity. Results showed that all 21 samples were detected with fungal contamination, and Ascomycota was dominant at the phylum level. In the groups based on collection areas, Dothideomycetes, Pleosporaceae, and Alternaria were dominant at the class, family, and genus levels, respectively. In the groups based on processing methods, Dothideomycetes, Aspergillaceae, and Alternaria were the most abundant at the class, family, and genus levels, respectively. Differences in fungal communities between various groups were also observed. Furthermore, a total of 115 species were identified, among which seven were potential toxigenic, namely, Trichothecium roseum, Alternaria tenuissima, Aspergillus carbonarius, Penicillium brevicompactum, Aspergillus fumigatus, Rhizopus microspores, and Pichia fermentans. In conclusion, this study reveals great fungal richness and diversity of Crataegi Fructus, providing references for the prevention and control of fungal contamination of Crataegi Fructus in practical production.

Immunosurveillance of Candida albicans commensalism by the adaptive immune system

The fungal microbiota (mycobiota) is an integral part of the microbial community colonizing the body surfaces and is involved in many key aspects of human physiology, while an imbalance of the fungal communities, termed fungal dysbiosis, has been described in pathologies ranging from infections to inflammatory bowel disease. Commensal organisms, such as the fungus Candida albicans, induce antigen-specific immune responses that maintain immune homeostasis. Adaptive immune mechanisms are vital in this process, while deficiencies in adaptive immunity are linked to fungal infections. We start to understand the mechanisms by which a shift in mycobiota composition, in particular in C. albicans abundance, is linked to immunopathological conditions. This review discusses the mechanisms that ensure continuous immunosurveillance of C. albicans during mucosal colonization, how these protective adaptive immune responses can also promote immunopathology, and highlight therapeutic advances against C. albicans-associated disease.

Intestinal Barrier Dysfunction in Fatty Liver Disease: Roles of Microbiota, Mucosal Immune System, and Bile Acids

Nonalcoholic fatty liver disease (NAFLD) describes a spectrum of progressive liver diseases ranging from simple steatosis to steatohepatitis and fibrosis. Globally, NAFLD is the leading cause of morbidity and mortality associated with chronic liver disease, and NAFLD patients are at a higher risk of developing cirrhosis and hepatocellular carcinoma. While there is a consensus that inflammation plays a key role in promoting NAFLD progression, the underlying mechanisms are not well understood. Recent clinical and experimental evidence suggest that increased hepatic translocation of gut microbial antigens, secondary to diet-induced impairment of the intestinal barrier may be important in driving hepatic inflammation in NAFLD. Here, we briefly review various endogenous and exogenous factors influencing the intestinal barrier and present recent advances in our understanding of cellular and molecular mechanisms underlying intestinal barrier dysfunction in NAFLD.

Roles for the mycobiome in liver disease

Liver disease, a major cause of global mortality, has been associated with dysbiosis of the intestinal microbiota (bacteria, fungi, viruses, and other microbes). Studies have associated changes in gut bacteria with pathogenesis and severity of liver disease, but the contributions of the mycobiome (the fungal populations of the gut) to health and disease have not been well studied. We review recent findings of alterations in the composition of the mycobiota in patients with liver disease and discuss the mechanisms by which these might affect pathogenesis and disease progression. Strategies to manipulate the gut mycobiota might be developed to treat or prevent liver disease.