Metagenomic analyses of alcohol induced pathogenic alterations in the intestinal microbiome and the effect of Lactobacillus rhamnosus GG treatment

Fibroblast growth factor 21 is required for the therapeutic effects of Lactobacillus rhamnosus GG against fructose-induced fatty liver in mice

Objectives

High fructose feeding changes fibroblast growth factor 21 (FGF21) regulation. Lactobacillus rhamnosus GG (LGG) supplementation reduces fructose-induced non-alcoholic fatty liver disease (NAFLD). The aim of this study was to determine the role of FGF21 and underlying mechanisms in the protective effects of LGG.

Methods

FGF21 knockout (KO) mice and C57BL/6 wild type (WT) mice were fed 30% fructose for 12 weeks. LGG was administered to the mice in the last 4 weeks during fructose feeding. FGF21-adiponectin (ADPN)-mediated hepatic lipogenesis and inflammation were investigated.

Results

FGF21 expression was robustly increased after 5-weeks of feeding and significantly decreased after 12-weeks of feeding in fructose-induced NAFLD mice. LGG administration reversed the depressed FGF21 expression, increased adipose production of ADPN, and reduced hepatic fat accumulation and inflammation in the WT mice but not in the KO mice. Hepatic nuclear carbohydrate responsive-element binding protein (ChREBP) was increased by fructose and reduced by LGG, resulting in a reduction in the expression of lipogenic genes. The methylated form of protein phosphatase 2A (PP2A) C, which dephosphorylates and activates ChREBP, was upregulated by fructose and normalized by LGG. Leucine carboxyl methyltransferase-1, which methylates PP2AC, was also increased by fructose and decreased by LGG. However, those beneficial effects of LGG were blunted in the KO mice. Hepatic dihydrosphingosine-1-phosphate, which inhibits PP2A, was markedly increased by LGG in the WT mice but attenuated in the KO mice. LGG decreased adipose hypertrophy and increased serum levels of ADPN, which regulates sphingosine metabolism. This beneficial effect was decreased in the KO mice.

Conclusion

LGG administration increases hepatic FGF21 expression and serum ADPN concentration, resulting in a reduced ChREBP activation through dihydrosphingosine-1-phosphate-mediated PP2A deactivation, and subsequently reversed fructose-induced NAFLD. Thus, our data suggest that FGF21 is required for the beneficial effects of LGG in reversal of fructose-induced NAFLD.

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Lactobacillus rhamnosus GG (LGG) attenuates fructose-induced NAFLD.

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LGG increases FGF21 and adiponectin expression.

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LGG inhibits fructose-activated ChREBP and reduces hepatic lipogenesis.

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FGF21 is required for the therapeutic effects of LGG against fructose-induced NAFLD.

Meta-analysis of alcohol induced gut dysbiosis and the resulting behavioral impact

About 99% of the unique genes and almost half of the cells found in the human body come from microbes including bacteria, archaea, fungi, and viruses. Collectively these microorganisms contribute to the microbiome and often reside in the gut. The gut microbiome plays an important role in the body and contributes to digestive health, the immune system, and brain function. The gut microbiome interacts with the central nervous system through the vagal pathways as well as the endocrine or immune pathways. Changes in the proportion or diversity of the microbiota can have an impact on normal physiology and has been implicated in inflammation, depression, obesity, and addiction. Several animal studies suggest the involvement of gut microbiome in the regulation of pain, emotion, and cognition. Alcoholism has been linked with gut microbiome dysbiosis and thus can have deleterious effects on the gut-brain axis balance. Gut microbiome produces important metabolites such as gastrointestinal hormones, short chain fatty acids, precursors to the neuroactive compounds and neurotransmitters that impact the physiology and normal functioning of the body. The microbiome imbalance has been correlated with behavioral changes and alcohol dependence in the host. The objective of this study is to elucidate the link between alcohol induced gut microbiota dysbiosis and any behavioral impact that could incur. A thorough literature search of various databases was conducted to gather data for the alcohol prompted gut microbiome dysbiosis. Ingenuity Pathway Analysis (IPA¹) software was then utilized to identify links between alcoholism, gut microbiome derived metabolites, and their role in behavior alterations. Overall, this meta-analysis reviews information available on the connection between alcohol induced gut microbiome dysbiosis and the resulting behavioral impact.

Fermented ginseng improved alcohol liver injury in association with changes in the gut microbiota of mice

The interactions among the liver, intestine and immune system play an important role in alcoholic liver injury. In this study, C57BL/6N mice with alcoholic injury were treated with unfermented and Lactobacillus fermentum KP-3-fermented ginseng. The indicators of hepatic steatosis, inflammation and injury were evaluated. The number of beneficial and harmful bacteria in the mice ileum and colon was counted by a traditional method; moreover, the diversity analysis of the cecum flora was performed. The alcohol exposure increased the levels of ALT, AST, TNF-α and IL-6 inflammatory factors and liver steatosis. In addition, the alcohol-fed miceexhibited a lower number of Lactobacilli and Bifidobacteria in the ileum and colon; the cecum flora diversity in the mice showed that alcohol obviously enhanced the abundance of the unclassified S24-7 of the Bacteroidetes phylum and the Proteobacteria genus of the Sutterella phylum and reduced the abundance of short-chain fatty acid-producing bacteria such as Akkermansia in the Verrucomicrobia phylum and those belonging to the Allobaculum genus, the Ruminococcus genus, and the Adlercreutzia genus in the Actinobacteria phylum. All these changes were improved by fermented ginseng. Conclusively, fermented ginseng could alleviate the alcoholic liver injury and disorder of the intestine by adjusting the intestinal flora.

The role of the gut microbiome in chronic liver disease: the clinical evidence revised

Recent research has suggested a role for the intestinal microbiota in the pathogenesis and potential treatment of a wide range of liver diseases. The intestinal microbiota and bacterial products may contribute to the development of liver diseases through multiple mechanisms including increased intestinal permeability, chronic systemic inflammation, production of short-chain fatty acids and changes in metabolism. This suggests a potential role for pre-, pro- and synbiotic products in the prevention or treatment of some liver diseases. In addition, there is emerging evidence on the effects of faecal microbial transplant. Herein, we discuss the relationship between the intestinal microbiota and liver diseases, as well as reviewing intestinal microbiota-based treatment options that are currently being investigated.

Emerging medical therapies for non-alcoholic fatty liver disease and for alcoholic hepatitis

Non-alcoholic fatty liver disease (NAFLD) and alcoholic liver disease (ALD) are currently the two most common liver diseases in the world. Alcoholic hepatitis (AH), a unique clinical syndrome among ALD patients has high short-term mortality. Apart from controlling the risk factor for individual respective disease, there are no Food and Drug Administration (FDA) approved medical therapies for these diseases. Over the last 5-10 years, the field has extensively grown with many new targets being studied in randomized clinical trials for these diseases, with many of these drugs being tested in both the conditions. In this chapter, we will describe the novel therapeutic agents and current status of ongoing clinical trials with these agents for the treatment of NAFLD and/or AH.

Effect on Viability of Microencapsulated Lactobacillus rhamnosus with the Whey Protein-pullulan Gels in Simulated Gastrointestinal Conditions and Properties of Gels

Lactobacillus rhamnosus GG (LGG) has low resistance to low pH and bile salt in the gastrointestinal juice. In this study, the gel made from whey protein concentrate (WPC) and pullulan (PUL) was used as the wall material to prepare the microencapsulation for LGG protection. The gelation process was optimized and the properties of gel were also determined. The results showed the optimal gel was made from 10% WPC and 8.0% PUL at pH 7.5, which could get the best protective effect; the viable counts of LGG were 6.61 Log CFU/g after exposure to simulated gastric juice (SGJ) and 9.40 Log CFU/g to simulated intestinal juice (SIJ) for 4 h. Sodium dodecyl sulphite polyacrylamide gel electrophoresis (SDS-PAGE) confirmed that the WPC-PUL gel had low solubility in SGJ, but dissolved well in SIJ, which suggested that the gel can protect LGG under SGJ condition and release probiotics in the SIJ. Moreover, when the gel has highest hardness and water-holding capacity, the viable counts of LGG were not the best, suggesting the relationship between the protection and the properties of the gel was non-linear.

Acetaminophen Intoxication Rapidly Induces Apoptosis of Intestinal Crypt Stem Cells and Enhances Intestinal Permeability

Acetaminophen (APAP)‐induced liver injury is the most common cause of acute liver failure (ALF) in the Western world. APAP toxicity progresses to multiorgan dysfunction and thus has broader whole‐body implications. Importantly, greater 30‐day mortality has been observed in liver transplant recipients following ALF due to APAP‐related versus non‐APAP‐related causes. Reasons for this discrepancy have yet to be determined. Extrahepatic toxicities of APAP overdose may represent underappreciated and unaddressed comorbidities within this patient population. In the present study, rapid induction of apoptosis following APAP overdose was observed in the intestine, an organ that greatly influences the physiology of the liver. Strikingly, apoptotic cells appeared to be strictly restricted to the intestinal crypts. The use of leucine‐rich repeat‐containing G protein–coupled receptor 5 (LGR5) reporter mice confirmed that the LGR5‐positive (+) crypt base stem cells were disproportionately affected by APAP‐induced cell death. Although the apoptotic cells were cleared within 24 hours after APAP treatment, potentially long‐lived consequences on the intestine due to APAP exposure were indicated by prolonged deficits in gut barrier function. Moreover, small intestinal cell death was found to be independent of tumor necrosis factor receptor signaling and may represent a direct toxic insult to the intestine by exposure to high concentrations of APAP. Conclusion: APAP induces intestinal injury through a regulated process of apoptotic cell death that disproportionately affects LGR5⁺ stem cells. This work advances our understanding of the consequences of APAP toxicity in a novel organ that was not previously considered as a significant site of injury and thus presents potential new considerations for patient management.

Effects of moderate, voluntary ethanol consumption on the rat and human gut microbiome

Many alcohol-induced health complications are directly attributable to the toxicity of alcohol or its metabolites, but another potential health impact of alcohol may be on the microbial communities of the human gut. Clear distinctions between healthy and diseased-state gut microbiota have been observed in subjects with metabolic diseases, and recent studies suggest that chronic alcoholism is linked to gut microbiome dysbiosis. Here, we investigated the effects of moderate levels of alcohol consumption on the gut microbiome in both rats and humans. The gut microbiota of rats voluntarily consuming a 20 percent ethanol solution, on alternate days, were compared with a non-exposed control group to identify differential taxonomic and functional profiles. Gut microbial diversity profiles were determined using culture-independent amplification, next-generation sequencing and bioinformatic analysis of bacterial 16S ribosomal RNA gene sequence libraries. Our results showed that, compared with controls, ethanol-consuming rats experienced a significant decline in the biodiversity of their gut microbiomes, a state generally associated with dysbiosis. We also observed significant shifts in the overall diversity of the gut microbial communities and a dramatic change in the relative abundance of particular microbes, such as the Lactobacilli. We also compared our results to human fecal microbiome data collected as part of the citizen science American Gut Project. In contrast to the rat data, human drinkers had significantly higher gut microbial biodiversity than non-drinkers. However, we also observed that microbes that differed among the human subjects displayed similar trends in the rat model, including bacteria implicated in metabolic disease.

Chalcone Derivative L6H21 Reduces EtOH + LPS-Induced Liver Injury Through Inhibition of NLRP3 Inflammasome Activation

BACKGROUND

Chronic alcohol intake increases circulating endotoxin levels causing excessive inflammation that aggravates the liver injury. (E)-2,3-dimethoxy-4'-methoxychalcone (L6H21), a derivative of chalcone, has been found to inhibit inflammation in cardiac diseases and nonalcoholic fatty liver disease. However, the use of L6H21 in alcoholic liver disease to inhibit exotoxin-associated inflammation has not been explored. In this study, we examined the effects of L6H21 on EtOH + LPS-induced hepatic inflammation, steatosis, and liver injury and investigated the underlying mechanisms.

METHODS

C57BL6 mice were treated with 5% EtOH for 10 days, and LPS was given to the mice 6 hours before sacrificing. One group of mice was supplemented with L6H21 with EtOH and LPS. RAW264.7 cells were used to analyze the effects of L6H21 on macrophage activation.

RESULTS

EtOH + LPS treatment significantly increased hepatic steatosis and serum levels of alanine transaminase (ALT) and aspartate transaminase (AST), which were reduced by L6H21 treatment. EtOH + LPS treatment increased hepatic inflammation, as shown by the increased hepatic protein levels of Toll-like receptor-4, p65, and p-IκB, and increased oxidative stress, as shown by protein carbonyl levels and reactive oxygen species formation, which were reduced by L6H21 treatment. In addition, L6H21 treatment markedly inhibited EtOH + LPS-elevated hepatic protein levels of NLRP3, cleaved caspase-1, cleaved IL-1β, and caspase-1-associated apoptosis.

CONCLUSIONS

Our results demonstrate that L6H21 treatment inhibits EtOH + LPS-induced liver steatosis and injury through suppression of NLRP3 inflammasome activation. L6H21 may be used as an alternative strategy for ALD prevention/treatment.

Hepatoprotective Effect of Probiotic Lactobacillus rhamnosus GG Through the Modulation of Gut Permeability and Inflammasomes in a Model of Alcoholic Liver Disease in Zebrafish

Objective: Alcoholic liver disease (ALD) is among the leading causes of death from liver disease. Among the factors involved in its pathogenesis are inflammation and increased intestinal permeability. The aim of this study was to assess the effect of Lactobacillus rhamnosus GG (LGG) on hepatic lipid accumulation, activation of inflammasomes, and gut permeability markers in experimental model of ALD with zebrafish.Methods: An experiment was conducted to assess the effective LGG dose capable of promoting intestinal colonization. Animals were divided into three groups (n = 64/group): ethanol group (E), ethanol + probiotic group (EP), and control group (C). Groups E and EP were exposed to 0.5% ethanol concentration for 28 days. At the end of this period, animals were euthanized, and livers were collected for Oil Red staining and assessment of the inflammasome system. Intestines were collected for evaluation of gut permeability markers.Results: The dose of 1.55 × 10⁶ UFC LGG/fish/d promoted intestinal colonization. Group EP presented lower hepatic lipid accumulation, lower il-1β expression, and higher cldn15a expression when compared to group E.Conclusions: Supplementation with LGG was protective for hepatic steatosis in ALD model. In addition, LGG influenced the modulation of the inflammatory response and markers of gut permeability, improving the gut barrier structure.

Are Probiotics Effective in Targeting Alcoholic Liver Diseases?

Alcoholic liver disease (ALD) encompasses a broad spectrum of disorders including steatosis, steatohepatitis, fibrosis, and cirrhosis. Despite intensive research in the last two decades, there is currently no Food and Drug Administration-approved therapy for treating ALD. Several studies have demonstrated the importance of the gut-liver axis and gut microbiome on the pathogenesis of ALD. Alcohol may induce intestinal dysbiosis and increased intestinal permeability, which in turn result in increased levels of pathogen-associated molecular patterns such as lipopolysaccharide (LPS) and translocation of microbial products from the gut to the liver (bacterial translocation). LPS is an inflammatory signal that activates toll-like receptor 4 on Kupffer cells, contributing to the inflammation observed in ALD. Recently, probiotics have been shown to be effective in reducing or preventing the progression of ALD. A potential mechanism is that the probiotics transforms the composition of intestinal microbiota, which leads to reductions in alcohol-induced dysbiosis, intestinal permeability, bacterial translocation, endotoxemia, and consequently, the development of ALD. While transformation of intestinal microbiota by probiotics appears to be a promising therapeutic strategy for the treatment of intestinal barrier dysfunction, there is a scarcity of research that studies probiotics in the context of ALD. In this review, we discuss the potential therapeutic applications of probiotics in the treatment of ALD.

Probiotics for Alleviating Alcoholic Liver Injury

Many animal experiments and clinical trials showed that probiotics are effective for the treatment of alcoholic liver disease. Alcohol disrupts the composition of intestinal flora; probiotics modulate the gut microbiota and reverse alcohol-associated intestinal barrier dysfunction by decreasing intestinal mucosal permeability and preventing intestinal bacteria from translocating. Probiotics enhance immune responses and reduce the levels of alcohol-induced inflammatory cytokines and reactive oxygen species (ROS) production in the liver and intestine. Probiotics also increase fatty acid β-oxidation and reduce lipogenesis, combating alcohol-induced hepatic steatosis. In this review, we summarize the current knowledge regarding the mechanism of action of probiotics for reducing the effects of alcoholic liver disease.

Linderae radix ethanol extract attenuates alcoholic liver injury via attenuating inflammation and regulating gut microbiota in rats

This study aimed to explore the influence of gut microbiota alterations induced by Linderae radix ethanol extract (LREE) on alcoholic liver disease (ALD) in rats and to study the anti-inflammatory effect of LREE on ALD through the lipopolysaccharide (LPS) toll-like receptor 4 (TLR4)-nuclear factor kappa B (NF-κB) pathway. ALD rat models were established by intragastric liquor [50% (v/v) ethanol] administration at 10 mL/kg body weight for 20 days. Rats were divided into six groups: normal group (no treatment), model group (ALD rats), Essentiale group (ALD rats fed with Essentiale, 137 mg/kg), and LREE high/moderate/low dose groups (ALD rats fed with 4, 2, or 1 g LREE/kg). NF-κB and LPS levels were evaluated. Liver pathological changes and intestinal ultrastructure were examined by hematoxylin and eosin staining and transmission electron microscopy. The gut microbiota composition was evaluated by 16S rDNA sequencing. Expression levels of TLR4 and CD68 in liver tissue, and occludin and claudin-1 in intestinal tissue were measured. LREE treatment significantly reduced NF-κB and LPS levels, improved liver pathological changes, and ameliorated intestinal ultrastructure injury. Meanwhile, LREE-fed groups showed a higher abundance of Firmicutes and a lower abundance of Bacteroidetes than the rats in the model group. Administration of LREE suppressed TLR4 overexpression and promoted the expression of occludin and claudin-1 in intestine tissue. Thus, LREE could partly ameliorate microflora dysbiosis, suppress the inflammatory response, and attenuate liver injury in ALD rats. The protective effect of LREE might be related to the LPS-TLR4-NF-κB pathway.

Role of Gut Microbiota in Hepatocarcinogenesis

Hepatocellular carcinoma (HCC), one of the leading causes of death worldwide, has a causal nexus with liver injury, inflammation, and regeneration that accumulates over decades. Observations from recent studies have accounted for the involvement of the gut–liver axis in the pathophysiological mechanism responsible for HCC. The human intestine nurtures a diversified colony of microorganisms residing in the host ecosystem. The intestinal barrier is critical for conserving the normal physiology of the gut microbiome. Therefore, a rupture of this barrier or dysbiosis can cause the intestinal microbiome to serve as the main source of portal-vein endotoxins, such as lipopolysaccharide, in the progression of hepatic diseases. Indeed, increased bacterial translocation is a key sign of HCC. Considering the limited number of clinical studies on HCC with respect to the microbiome, we focus on clinical as well as animal studies involving the gut microbiota, with the current understandings of the mechanism by which the intestinal dysbiosis promotes hepatocarcinogenesis. Future research might offer mechanistic insights into the specific phyla targeting the leaky gut, as well as microbial dysbiosis, and their metabolites, which represent key pathways that drive HCC-promoting microbiome-mediated liver inflammation and fibrosis, thereby restoring the gut barrier function.

A potential role for the gut microbiome in substance use disorders

Pathological substance use disorders represent a major public health crisis with limited effective treatment options. While much work has been done to understand the neuronal signaling networks and intracellular signaling cascades associated with prolonged drug use, these studies have yielded few successful treatment options for substance use disorders. In recent years, there has been a growing interest to explore interactions between the peripheral immune system, the gut microbiome, and the CNS. In this review, we will present a summary of existing evidence, suggesting a potential role for gut dysbiosis in the pathogenesis of substance use disorders. Clinical evidence of gut dysbiosis in human subjects with substance use disorder and preclinical evidence of gut dysbiosis in animal models of drug addiction are discussed in detail. Additionally, we examine how changes in the gut microbiome and its metabolites may not only be a consequence of substance use disorders but may in fact play a role in mediating behavioral response to drugs of abuse. While much work still needs to be done, understanding the interplay of gut microbiome in substance use disorders may offer a promising avenue for future therapeutic development.

Do your gut microbes affect your brain dopamine?

Increasing evidence shows changes in gut microbiota composition in association with psychiatric disorders, including anxiety and depression. Moreover, it has been reported that perturbations in gut microbe diversity and richness influence serotonergic, GABAergic, noradrenergic, and dopaminergic neurotransmission. Among these, dopamine is regarded as a main regulator of cognitive functions such as decision making, attention, memory, motivation, and reward. In this work, we will highlight findings that link alterations in intestinal microbiota and dopaminergic neurotransmission, with a particular emphasis on the mesocorticolimbic circuit, which is involved in reward to natural reinforcers, as well as abuse substances. For this, we reviewed evidence from studies carried out on germ-free animals, or in rodents subjected to intestinal dysbiosis using antibiotics, and also through the use of probiotics. All this evidence strongly supports that the microbiota-gut-brain axis is key to the physiopathology of several neuropsychiatric disorders involving those where dopaminergic neurotransmission is compromised. In addition, the gut microbiota appears as a key player when it comes to proposing novel strategies to the treatment of these psychiatric conditions.

Alcohol-induced changes in the gut microbiome and metabolome of rhesus macaques

RATIONALE

Increasing evidence has demonstrated that changes in the gut microbiome, including those associated with dietary influences, are associated with alterations in many physiological processes. Alcohol consumption is common across human cultures and is likely to have a major effect on the gut microbiome, but there remains a paucity of information on its effects in primates.

OBJECTIVES

The effects of chronic alcohol consumption on the primate gut microbiome and metabolome were studied in rhesus macaques that were freely drinking alcohol. The objectives of the study were to determine what changes occurred in the gut microbiome following long-term exposure to alcohol and if these changes were reversible following a period of abstinence.

METHODS

Animals consuming alcohol were compared to age-matched controls without access to alcohol and were studied before and after a period of abstinence. Fecal samples from rhesus macaques were used for 16S rRNA sequencing to profile the gut microbiome and for metabolomic profiling using mass spectrometry.

RESULTS

Alcohol consumption resulted in a loss of alpha-diversity in rhesus macaques, though this was partially ameliorated by a period of abstinence. Higher levels of Firmicutes were observed in alcohol-drinking animals at the expense of a number of other microbial taxa, again normalizing in part with a period of abstinence. Metabolomic changes were primarily associated with differences in glycolysis when animals were consuming alcohol and differences in fatty acids when alcohol-drinking animals became abstinent.

CONCLUSIONS

The consumption of alcohol has specific effects on the microbiome and metabolome of rhesus macaques independent of secondary influences. Many of these changes are reversed by a relatively short period of abstinence.

The Impact of Past and Current Alcohol Consumption Patterns on Progression of Carotid Intima-Media Thickness Among Women and Men Living with HIV Infection

BACKGROUND

The relationship between alcohol consumption and atherosclerosis has not been sufficiently examined among people living with HIV (PLWH).

METHODS

We analyzed data from PLWH in the Women's Interagency HIV Study (WIHS; n = 1,164) and the Multicenter AIDS Cohort Study (MACS; n = 387) with no history of cardiovascular disease (CVD). Repeated measures of intima-media thickness of the right common carotid artery (CCA-IMT) were assessed using B-mode ultrasound from 2004 to 2013. Current alcohol consumption was collected at time of CCA-IMT measurement and was categorized according to gender-specific weekly limits. Group-based trajectory models categorized participants into past 10-year consumption patterns (1994 to 2004). Multivariate generalized estimating equations were conducted to assess the association of past and current alcohol use patterns on change in CCA-IMT by cohort, controlling for age, race, cigarette and illicit drug use, probable depression, HIV RNA viral load, antiretroviral therapy exposure, and hepatitis C coinfection.

RESULTS

Among the WIHS, past heavy alcohol consumption was associated with increased CCA-IMT level over time (β = 8.08, CI 0.35, 15.8, p = 0.04), compared to abstinence. Among the MACS, compared to abstinence, all past consumption patterns were associated with increased CCA-IMT over time (past low: β = 15.3, 95% CI 6.46, 24.2, p < 0.001; past moderate: β = 14.3, CI 1.36, 27.2, p = 0.03; past heavy: β = 21.8, CI 4.63, 38.9, p = 0.01). Current heavy consumption was associated with decreased CCA-IMT among the WIHS (β = -11.4, 95% CI -20.2, -2.63, p = 0.01) and MACS (β = -15.4, 95% CI -30.7, -0.13, p = 0.04). No statistically significant time by consumption pattern effects were found.

CONCLUSIONS

In both cohorts, 10-year heavy consumption was associated with statistically significant increases in carotid artery thickness, compared to abstinence. Long-term patterns of drinking at any level above abstinence were particularly significant for increases in IMT among men, with heavy consumption presenting with the greatest increase. Our results suggest a potentially different window of risk among past and current heavy drinkers. Further studies are needed to determine whether alcohol consumption level is associated with intermediate measures of atherosclerosis. Alcohol screening and interventions to reduce heavy consumption may benefit PLWH who are at risk of CVD.

Alcohol, liver disease and the gut microbiota

Alcoholic liver disease, which ranges from mild disease to alcoholic hepatitis and cirrhosis, is a leading cause of morbidity and mortality worldwide. Alcohol intake can lead to changes in gut microbiota composition, even before liver disease development. These alterations worsen with advancing disease and could be complicit in disease progression. Microbial function, especially related to bile acid metabolism, can modulate alcohol-associated injury even in the presence of cirrhosis and alcoholic hepatitis. Microbiota changes might also alter brain function, and the gut-brain axis might be a potential target to reduce alcoholic relapse risk. Gut microbiota manipulation including probiotics, faecal microbial transplant and antibiotics has been studied in alcoholic liver disease with varying success. Further investigation of the modulation of the gut-liver axis is relevant, as most of these patients are not candidates for liver transplantation. This Review focuses on clinical studies involving the gut microbiota in patients with alcoholic liver disease across the spectrum from alcoholic fatty liver to cirrhosis and alcoholic hepatitis. Specific alterations in the gut-liver-brain axis that are complicit in the interactions between the gut microbiota and alcohol addiction are also reviewed.

Characterization of gut microbiota composition and functions in patients with chronic alcohol overconsumption

Excessive alcohol intake can alter the gut microbiota, which may underlie the pathophysiology of alcohol-related diseases. We examined gut microbiota composition and functions in patients with alcohol overconsumption for >10 years, compared to a control group of patients with a history of no or low alcohol intake. Faecal microbiota composition was assessed by 16S rRNA sequencing. Gut microbiota functions were evaluated by quantification of short-chain fatty acids (SCFAs) and predictive metagenome profiling (PICRUSt). Twenty-four patients, mean age 64.8 years (19 males), with alcohol overconsumption, and 18 control patients, mean age 58.2 years (14 males) were included. The two groups were comparable regarding basic clinical variables. Nutritional assessment revealed lower total score on the screening tool Mini Nutritional Assessment, lower muscle mass as assessed by handgrip strength, and lower plasma vitamin C levels in the alcohol overconsumption group. Bacteria from phylum Proteobacteria were found in higher relative abundance, while bacteria from genus Faecalibacterium were found in lower relative abundance in the group of alcohol overconsumers. The group also had higher levels of the genera Sutterella, Holdemania and Clostridium, and lower concentration and percentage of butyric acid. When applying PICRUSt to predict the metagenomic composition, we found that genes related to invasion of epithelial cells were more common in the group of alcohol overconsumers. We conclude that gut microbiota composition and functions in patients with alcohol overconsumption differ from patients with low consumption of alcohol, and seem to be skewed into a putative pro-inflammatory direction.

Chronic alcohol exposure induced gut microbiota dysbiosis and its correlations with neuropsychic behaviors and brain BDNF/Gabra1 changes in mice

Alcohol addiction can cause brain dysfunction and many other diseases. Recently, increasing evidences have suggested that gut microbiota plays a vital role in regulating alcohol addiction. However, the exact mechanism has not yet been elucidated. Here, our study focused on the intestinal bacteria alternations and their correlations with alcohol-induced neuropsychic behaviors. When consuming alcohol over 3-week period, animals gradually displayed anxiety/depression-like behaviors. Moreover, 16S rRNA sequencing showed significant intestinal microflora dysbiosis and distinct community composition. Actinobacteria and Cyanobacteria were both increased at the phylum level. At the genus level, Adlercreutzia spp., Allobaculum spp., and Turicibacter spp. were increased whereas Helicobacter spp. was decreased. We also found that the distances in inner zone measured by open field test and 4% (v/v) alcohol preference percentages were significantly correlated with Adlercreutzia spp. The possible mechanisms were explored and we found the expression of brain-derived neurotrophic factor (BDNF) and α1 subunit of γ-aminobutyric acid A receptor (Gabra1) were both decreased in prefrontal cortex (PFC). Especially, further correlation analyses demonstrated that decreased Adlercreutzia spp. was positively correlated with alcohol preference and negatively correlated with anxiety-like behavior and BDNF/Gabra1 changes in PFC. Similar relationships were observed between Allobaculum spp. and alcohol preference and BDNF changes. Helicobacter spp. and Turicibacter spp. were also correlated with PFC BDNF and hippocampus Gabra1 level. Taken together, our study showed that gut microbiota dysbiosis during chronic alcohol exposure was closely correlated with alcohol-induced neuropsychic behaviors and BDNF/Gabra1 expression, which provides a new perspective for understanding underlying mechanisms in alcohol addiction. © 2018 BioFactors, 45(2):187-199, 2019.

Histopathological Features and Composition of Gut Microbiota in Rhesus Monkey of Alcoholic Liver Disease

Alcohol-induced chronic liver disease (ALD) is becoming the most common liver disease in the world. However, there are no effective, universally accepted therapies for ALD. The etiology of ALD remains blurry so far. Historical evidence has demonstrated a link between the liver and gut microbiota. But it is difficult to distinguish the effect of gut microbiota changes caused by alcohol consumption in humans since the microbiota change detected in humans is complicated by diet and environmental factors. Due to the genetic, physiological, metabolic, and behavioral similarities to humans, the rhesus monkey provides excellent translational validity in preclinical studies, and the diet and environmental conditions can be controlled well in rhesus monkey. In our study, we explored the relationship between ALD and the gut microbiome in the rhesus monkeys with alcoholic liver steatosis. Our results showed that there was a change of the bacterial community structure in monkeys with ALD. Differences of the relative abundances of gut microbiota at phylum, order, family, genus, and species levels were observed between control monkeys and monkeys with ALD, and different pathways enriched in the monkeys with ALD were identified by metagenomic function analysis. Firmicutes, Proteobacteria, Verrucomicrobia tended to increase whereas Bacteroidetes and Actinobacteria decreased in the fecal microbiota of ALD group compared to the control group. Lactobacillales and Lactobacillus significantly decreased in ALD monkeys compared with normal monkeys, Streptococcus was lower in the ALD group compared with the control group. The non-human primate model of ALD will be useful for exploration of the microbiome markers as diagnosis and potentially prognosis for ALD. The ALD model will benefit the development of new therapeutic procedures for treating ALD and provide safety and efficacy evaluation for clinical application.

Microbiome as a therapeutic target in alcohol-related liver disease

Alcohol-related liver disease is associated with significant changes in gut microbial composition. The transmissibility of ethanol-induced liver disease has been demonstrated using faecal microbiota transfer in preclinical models. This technique has also led to improved survival in patients with severe alcoholic hepatitis, suggesting that changes in the composition and function of the gut microbiota are causatively linked to alcohol-related liver disease. A major mechanism by which gut microbiota influence the development of alcohol-related liver disease is through a leaky intestinal barrier. This permits translocation of viable bacteria and microbial products to the liver, where they induce and promote inflammation, as well as contribute to hepatocyte death and the fibrotic response. In addition, gut dysbiosis is associated with changes in the metabolic function of the intestinal microbiota, bile acid composition and circulation, immune dysregulation during onset and progression of alcohol-related liver disease. Findings from preclinical and human studies will be used to demonstrate how alcohol causes intestinal pathology and contributes to alcohol-related liver disease and how the latter is self-perpetuating. Additionally, we summarise the effects of untargeted treatment approaches on the gut microbiota, such as diet, probiotics, antibiotics and faecal microbial transplantation in alcohol-related liver disease. We further discuss how targeted approaches can restore intestinal homeostasis and improve alcohol-related liver disease. These approaches are likely to add to the therapeutic options for alcohol-related liver disease independently or in conjunction with steroids.

Pathogenesis of Alcoholic Liver Disease: An Update

Apart from the classic knowledge that ethanol mediates its hepatotoxicity through its metabolism to acetaldehyde, a well-known hepatotoxic molecule, recent research has elucidated several key mechanisms that potentiate ethanol's damage to the liver parenchyma, such as generation of free radicals, activation of Kupffer cells, and alterations to the human bacterial and fungal microbiome. Genetic studies have suggested the role of PNPLA3 and TM6SF2 gene mutations in the progression of alcoholic liver disease.

Current trials and novel therapeutic targets for alcoholic hepatitis

Alcoholic hepatitis is a clinical syndrome in which patients present with acute-on-chronic liver failure and a high risk of short-term mortality. The current treatment of alcoholic hepatitis is suboptimal. Results recently published from the STOPAH study have improved our understanding of how best to design clinical trials for this condition. Although emerging data on liver transplantation for patients with alcoholic hepatitis are encouraging, less than 2% of these patients qualify. Clearly, there is an unmet need for novel treatments to improve the survival of these patients. Changes in the gut microbiota, inflammatory and cytokine signalling, oxidative stress and mitochondrial dysfunction, and abnormalities in the hepatic regenerative capacity alone or in combination contribute to the pathology of alcoholic hepatitis. In this chapter, we will describe the novel therapeutic agents targeting various pathways in the pathophysiology of alcoholic hepatitis. Specifically, we will describe the ongoing clinical trials in which some of these agents are being studied.

Targeting gut microbiota with dietary components on cancer: Effects and potential mechanisms of action

Cancers are common chronic diseases worldwide and cause severe health burdens. There have been ongoing debates on the role of gut microbiota in the prevention and management of cancers, thus, it is worthwhile to pay high attention to the impacts of gut microbiota on several cancers, such as colon, liver, and breast cancers. In addition, it has been reported that gut microbiota may also affect the efficacy of cancer chemotherapy and immunotherapy. Among all the factors that influence gut microbiota, diet is the most influential and modifiable. The prebiotics, dietary fibers, short-chain fatty acids, and other bioactive compounds are all important dietary components to assist the growth of beneficial microbiota in the gut, which can protect against cancers and promote human health. Their beneficial effects can be due to the fermentation of dietary fibers, the metabolism of phytochemicals, the synthesis of estrogens, and interactions with chemotherapies and immunotherapies. In order to provide updated information of the relationships among dietary components, gut microbiota, and cancer, in this review, we summarize the reciprocal interactions between dietary components and gut microbiota, and highlight the impacts of dietary components on several common cancers by targeting gut microbiota, with the potential mechanisms of actions also intensively discussed. As a result, this review can be very helpful for healthy people as well as cancer patients to prevent or manage cancers via dietary factor-mediated regulation of gut microbiota.

Alcoholic liver disease and intestinal microecology

Alcoholic liver disease (ALD) is damage to the liver that occurs after excessive alcohol use over a long period of time, which is mainly characterized by hepatocyte steatosis and fat storage, and the disease spectrum includes steatosis, steatohepatitis, alcoholic fibrosis, and cirrhosis. Steatosis and early steatohepatitis are reversible after cessation of alcohol use. Although the pathogenesis of ALD is not yet fully understood, many studies have shown that the intestinal microecological dysbiosis is closely related to the occurrence and development of ALD. Chronic alcohol use may cause intestinal microecological dysbiosis by leading to increased intestinal mucosal permeability, intestinal flora imbalance, and bacterial translocation, which can then activate immune response, induce an inflammatory response in the liver, and thus lead to liver damage. Based on this situation, we can adjust the intestinal flora imbalance to achieve the goal of treating ALD by using various methods such as supplementing probiotics or prebiotics, properly using antibiotics, and performing fecal microbiota transplantation. In addition, targeted therapy for intestinal bacterial imbalance has also become a hotspot in current research.

Environmental Factors, Gut Microbiota, and Colorectal Cancer Prevention

The substantial burden of colorectal cancer and increasing trend in young adults highlight the importance of lifestyle modification as a complement to screening for colorectal cancer prevention. Several dietary and lifestyle factors have been implicated in the development of colorectal cancer, possibly through the intricate metabolic and inflammatory mechanisms. Likewise, as a key metabolic and immune regulator, the gut microbiota has been recognized to play an important role in colorectal tumorigenesis. Increasing data support that environmental factors are crucial determinants for the gut microbial composition and function, whose alterations induce changes in the host gene expression, metabolic regulation, and local and systemic immune response, thereby influencing cancer development. Here, we review the epidemiologic and mechanistic evidence regarding the links between diet and lifestyle and the gut microbiota in the development of colorectal cancer. We focus on factors for which substantial data support their importance for colorectal cancer and their potential role in the gut microbiota, including overweight and obesity, physical activity, dietary patterns, fiber, red and processed meat, marine omega-3 fatty acid, alcohol, and smoking. We also briefly describe other colorectal cancer-preventive factors for which the links with the gut microbiota have been suggested but remain to be mechanistically characterized, including vitamin D status, dairy consumption, and metformin use. Given limitations in available evidence, we highlight the need for further investigations in the relationship between environmental factors, gut microbiota, and colorectal cancer, which may lead to development and clinical translation of potential microbiota-based strategies for cancer prevention.

Semen hoveniae extract ameliorates alcohol-induced chronic liver damage in rats via modulation of the abnormalities of gut-liver axis

BACKGROUND

Hovenia dulcis Thunb. is considered as a traditional herbal medicine that has been used in the treatment for ethanol-induced liver disease for centuries. Recently, substantial studies demonstrated that Semen hoveniae extract (SHE) not only suppressed the hepatic steatosis caused by chronic ethanol exposure, but also inhibited lipopolysaccharide-stimulated inflammatory responses. Nevertheless, the underlying molecular mechanisms largely remained elusive.

AIM

To determine the hepatoprotective effects of SHE on ethanol-triggered liver damage and further elucidate its potential mechanisms.

METHODS

In the present study, the Sprague-Dawley rats were fed with the Lieber-DeCarli diet containing alcohol or isocaloric maltose dextrin as control diet with or without SHE (300 and 600 mg/kg/d bw) for 8 weeks. The levels of serum biomarkers (ALT, AST and LDH) and LPS were detected by biochemical assay kits and endotoxin detection LAL kit, respectively. The histopathological changes of liver and intestinal tissues were observed by hematoxylin and eosin (H&E) staining and Transmission electron microscope (TEM). The expressions of CD14, TLR4, MyD88, NF-κB, Iκ-B, P-Iκ-B and TNF-α in liver, and ZO-1 and occludin in intestine were determined by western blot. The faecal microbial composition was determined by16S rRNA Gene Sequencing Analysis.

RESULTS

Biochemical and histopathological analysis revealed that SHE significantly alleviated the lipid deposition and inflammation response in liver induced by ethanol. SHE remarkably inhibited the TLR4 pathway and its downstream inflammatory mediators, and up-regulated the expressions of ZO-1 and occludin in the intestine. The further investigations suggested SHE dramatically reversed ethanol-induced alterations in the intestinal microbial flora and decreased the generation of gut-derived endotoxin.

CONCLUSION

In summary, SHE probably modulated abnormalities of gut-liver axis and inhibited TLR4-associated inflammatory mediators activation to exert its hepatoprotective properties. These findings suggested that SHE as a traditional therapeutic options which may play an essential role in protecting against the chronic ethanol-triggered liver injury.

Supplementation of okra seed oil ameliorates ethanol-induced liver injury and modulates gut microbiota dysbiosis in mice

This study assesses the possible effects of dietary okra seed oil (OSO) consumption on attenuation of alcohol-induced liver damage and gut microbiota dysbiosis, and associated mechanisms in mice.

Following spinal cord injury, PDE4B drives an acute, local inflammatory response and a chronic, systemic response exacerbated by gut dysbiosis and endotoxemia

Emerging evidence links changes in the gut microbiome and intestinal barrier function to alterations in CNS function. We examined the role of endotoxin-responsive, cAMP-specific, Pde4 subfamily b (Pde4b) enzyme in gut dysbiosis induced neuro-inflammation and white matter loss following spinal cord injury (SCI). Using a thoracic contusion model in C57Bl/6 wild type female mice, SCI led to significant shifts in the gut bacterial community including an increase in the phylum Proteobacteria, which consists of endotoxin-harboring, gram-negative bacteria. This was accompanied by increased systemic inflammatory marker, soluble CD14, along with markers of the endoplasmic reticulum stress response (ERSR) and inflammation in the SCI epicenter. Deletion of Pde4b reduced epicenter expression of markers for the ERSR and inflammation, at both acute and chronic time points post-SCI. Correspondingly, expression of oligodendrocyte mRNAs increased. Within the injury penumbra, inflammatory protein markers of activated astrocytes (GFAP), macrophage/microglia (CD11b, Iba1), and the proinflammatory mediator Cox2, were decreased in Pde4b^-/- mice. The absence of Pde4b improved white matter sparing and recovery of hindlimb locomotion following injury. Importantly, SCI-induced gut dysbiosis, bacterial overgrowth and endotoxemia were also prevented in Pde4b^-/- mice. Taken together, these findings indicate that PDE4B plays an important role in the development of acute and chronic inflammatory response and consequent recovery following SCI.

Porphyromonas gingivalis as a Possible Risk Factor in the Development/Severity of Acute Alcoholic Hepatitis

Bacterial infection is frequently observed in patients with alcoholic liver disease (ALD). We examined a possible role of Porphyromonas gingivalis in the development/progression and severity of disease in patients with acute alcoholic hepatitis (AAH). Plasma specimens from 47 patients with AAH (16 moderate, Model for End‐Stage Liver Disease [MELD] score <20]; 31 severe, MELD score >20) and 22 healthy controls (HCs) were collected. Clinical, drinking history (lifetime drinking history [LTDH]), and demographic data were collected. Antibody tests for immunoglobulin (Ig) G, IgM, and IgA against two P. gingivalis strains were performed. Between‐group comparisons and within‐group association analyses were carried out. Patients with severe AAH showed significantly higher plasma levels of IgG, IgA, and IgM against two P. gingivalis strains (W83 and 33277) compared to HCs. Patients with moderate AAH also had significantly elevated anti‐P. gingivalis IgA concentrations for both strains compared to HCs. Male patients with moderate AAH showed a significant inverse association in LTDH and anti‐P. gingivalis IgM. The aspartate aminotransferase:alanine aminotransferase ratio was positively associated with IgM of both strains in male patients with moderate AAH. Female patients with severe AAH showed a significant association between MELD scores and W83 IgM. Conclusion: Antibody response to P. gingivalis in AAH is elevated. Significantly elevated plasma anti‐P. gingivalis IgG, IgA, and IgM in severe AAH provide preliminary data that P. gingivalis could be a novel risk factor in the development/severity of AAH.

Publisher Correction: The gut-liver axis and the intersection with the microbiome

In the original version of Table 1 published online, upward arrows to indicate increased translocation of PAMPs were missing from the row entitled 'Translocation' for both the column on alcoholic liver disease and nonalcoholic fatty liver disease. This error has now been updated in the PDF and HTML version of the article.

Liver Injury, Endotoxemia, and Their Relationship to Intestinal Microbiota Composition in Alcohol-Preferring Rats

BACKGROUND

There is strong evidence that alcoholism leads to dysbiosis in both humans and animals. However, it is unclear how changes in the intestinal microbiota (IM) relate to ethanol (EtOH)-induced disruption of gut-liver homeostasis. We investigated this issue using selectively bred Sardinian alcohol-preferring (sP) rats, a validated animal model of excessive EtOH consumption.

METHODS

Independent groups of male adult sP rats were exposed to the standard, home-cage 2-bottle "EtOH (10% v/v) versus water" choice regimen with unlimited access for 24 h/d (Group Et) for 3 (T1), 6 (T2), and 12 (T3) consecutive months. Control groups (Group Ct) were composed of matched-age EtOH-naïve sP rats. We obtained samples from each rat at the end of each experimental time, and we used blood and colon tissues for intestinal barrier integrity and/or liver pathology assessments and used stool samples for IM analysis with 16S ribosomal RNA gene sequencing.

RESULTS

Rats in Group Et developed hepatic steatosis and elevated serum transaminases and endotoxin/lipopolysaccharide (LPS) levels but no other liver pathological changes (i.e., necrosis/inflammation) or systemic inflammation. While we did not find any apparent alteration of the intestinal colonic mucosa, we found that rats in Group Et exhibited significant changes in IM composition compared to the rats in Group Ct. These changes were sustained throughout T1, T2, and T3. In particular, Ruminococcus, Coprococcus, and Streptococcus were the differentially abundant microbial genera at T3. The KEGG Ortholog profile revealed that IM functional modules, such as biosynthesis, transport, and export of LPS, were also enriched in Group Et rats at T3.

CONCLUSIONS

We showed that chronic, voluntary EtOH consumption induced liver injury and endotoxemia together with dysbiotic changes in sP rats. This work sets the stage for improving our knowledge of the prevention and treatment of EtOH-related diseases.

Intestinal HIF-1α deletion exacerbates alcoholic liver disease by inducing intestinal dysbiosis and barrier dysfunction

BACKGROUND & AIMS

Alcoholic liver disease (ALD) is characterized by gut dysbiosis and increased gut permeability. Hypoxia inducible factor 1α (HIF-1α) has been implicated in transcriptional regulation of intestinal barrier integrity and inflammation. We aimed to test the hypothesis that HIF-1α plays a critical role in gut microbiota homeostasis and the maintenance of intestinal barrier integrity in a mouse model of ALD.

METHODS

Wild-type (WT) and intestinal epithelial-specific Hif1a knockout mice (IEhif1α^-/-) were pair-fed modified Lieber-DeCarli liquid diet containing 5% (w/v) alcohol or isocaloric maltose dextrin for 24 days. Serum levels of alanine aminotransferase and endotoxin were determined. Fecal microbiota were assessed. Liver steatosis and injury, and intestinal barrier integrity were evaluated.

RESULTS

Alcohol feeding increased serum levels of alanine aminotransferase and lipopolysaccharide, hepatic triglyceride concentration, and liver injury in the WT mice. These deleterious effects were exaggerated in IEhif1α^-/- mice. Alcohol exposure resulted in greater reduction of the expression of intestinal epithelial tight junction proteins, claudin-1 and occludin, in IEhif1α^-/- mice. In addition, cathelicidin-related antimicrobial peptide and intestinal trefoil factor were further decreased by alcohol in IEhif1α^-/- mice. Metagenomic analysis showed increased gut dysbiosis and significantly decreased Firmicutes/Bacteroidetes ratio in IEhif1α^-/- mice compared to the WT mice exposed to alcohol. An increased abundance of Akkermansia and a decreased level of Lactobacillus in IEhif1α^-/- mice were also observed. Non-absorbable antibiotic treatment reversed the liver steatosis in both WT and IEhif1α^-/- mice.

CONCLUSION

Intestinal HIF-1α is essential for the adaptative response to alcohol-induced changes in intestinal microbiota and barrier function associated with elevated endotoxemia and hepatic steatosis and injury.

LAY SUMMARY

Alcohol consumption alters gut microbiota and multiple intestinal barrier protecting factors that are regulated by intestinal hypoxia-inducible factor 1α (HIF-1α). Absence of intestinal HIF-1α exacerbates gut leakiness leading to an increased translocation of bacteria and bacterial products to the liver, consequently causing alcoholic liver disease. Intestinal specific upregulation of HIF-1α could be developed as a novel approach for the treatment of alcoholic liver disease.

Colorectal carcinogenesis: an archetype of gut microbiota-host interaction

Sporadic colorectal cancer (CRC) remains a major cause of worldwide mortality. Epidemiological evidence of markedly increased risk in populations that migrate to Western countries, or adopt their lifestyle, suggests that CRC is a disease whose aetiology is defined primarily by interactions between the host and his environment. The gut microbiome sits directly at this interface and is now increasingly recognised as a modulator of colorectal carcinogenesis. Bacteria such as Fusobacterium nucleatum and Escherichia coli (E. Coli) are found in abundance in patients with CRC and have been shown in experimental studies to promote neoplasia. A whole armamentarium of bacteria-derived oncogenic mechanisms has been defined, including the subversion of apoptosis and the production of genotoxins and pro-inflammatory factors. But the microbiota may also be protective: for example, they are implicated in the metabolism of dietary fibre to produce butyrate, a short chain fatty acid, which is anti-inflammatory and anti-carcinogenic. Indeed, although our understanding of this immensely complex, highly individualised and multi-faceted relationship is expanding rapidly, many questions remain: Can we define friends and foes, and drivers and passengers? What are the critical functions of the microbiota in the context of colorectal neoplasia?

Pomegranate prevents binge alcohol-induced gut leakiness and hepatic inflammation by suppressing oxidative and nitrative stress

Alcoholic liver disease (ALD) is a major chronic liver disease worldwide and can range from simple steatosis, inflammation to fibrosis/cirrhosis possibly through leaky gut and systemic endotoxemia. We investigated whether pomegranate (POM) protects against binge alcohol-induced gut leakiness, endotoxemia, and inflammatory liver damage. After POM pretreatment for 10 days, rats were exposed to 3 oral doses of binge alcohol (5 g/kg/dose) or dextrose (as control) at 12-h intervals. Binge alcohol exposure induced leaky gut with significantly elevated plasma endotoxin and inflammatory fatty liver by increasing the levels of oxidative and nitrative stress marker proteins such as ethanol-inducible CYP2E1, inducible nitric oxide synthase, and nitrated proteins in the small intestine and liver. POM pretreatment significantly reduced the alcohol-induced gut barrier dysfunction, plasma endotoxin and inflammatory liver disease by inhibiting the elevated oxidative and nitrative stress marker proteins. POM pretreatment significantly restored the levels of intestinal tight junction (TJ) proteins such as ZO-1, occludin, claudin-1, and claundin-3 markedly diminished after alcohol-exposure. In addition, the levels of gut adherent junction (AJ) proteins (e.g., β-catenin and E-cadherin) and desmosome plakoglobin along with associated protein α-tubulin were clearly decreased in binge alcohol-exposed rats but restored to basal levels in POM-pretreated rats. Immunoprecipitation followed by immunoblot analyses revealed that intestinal claudin-1 protein was nitrated and ubiquitinated in alcohol-exposed rats, whereas these modifications were significantly blocked by POM pretreatment. These results showed for the first time that POM can prevent alcohol-induced gut leakiness and inflammatory liver injury by suppressing oxidative and nitrative stress.

Tributyrin Supplementation Protects Immune Responses and Vasculature and Reduces Oxidative Stress in the Proximal Colon of Mice Exposed to Chronic-Binge Ethanol Feeding

Excessive ethanol consumption causes adverse effects and contributes to organ dysfunction. Ethanol metabolism triggers oxidative stress, altered immune function, and gut dysbiosis. The gut microbiome is known to contribute to the maintenance of intestinal homeostasis, and disturbances are associated with pathology. A consequence of gut dysbiosis is also alterations in its metabolic and fermentation byproducts. The gut microbiota ferments undigested dietary polysaccharides to yield short-chain fatty acids, predominantly acetate, propionate, and butyrate. Butyrate has many biological mechanisms of action including anti-inflammatory and immunoprotective effects, and its depletion is associated with intestinal injury. We previously showed that butyrate protects gut-liver injury during ethanol exposure. While the intestine is the largest immune organ in the body, little is known regarding the effects of ethanol on intestinal immune function. This work is aimed at investigating the effects of butyrate supplementation, in the form of the structured triglyceride tributyrin, on intestinal innate immune responses and oxidative stress following chronic-binge ethanol exposure in mice. Our work suggests that tributyrin supplementation preserved immune responses and reduced oxidative stress in the proximal colon during chronic-binge ethanol exposure. Our results also indicate a possible involvement of tributyrin in maintaining the integrity of intestinal villi vasculature disrupted by chronic-binge ethanol exposure.

Gut Microbiota and Relevant Metabolites Analysis in Alcohol Dependent Mice

Alcohol abuse is a major public health crisis. Relative evidences supported that the gut microbiota (GM) played an important role in central nervous system (CNS) function, and the composition of them had changed after alcohol drinking. We sought to explore the changes of GM in alcohol dependence. In our study, the GM of mice with alcohol administration was detected through analyzed 16S rRNA gene sequencing and the fecal metabolites were analyzed by LC-MS. The microbial diversity was significantly higher in the alcohol administration group, the abundance of phylum Firmicutes and its class Clostridiales were elevated, meanwhile the abundance of Lachnospiraceae, Alistipes, and Odoribacter showed significant differences among the three groups. Based on LC-MS results, bile acid, secondary bile acid, serotonin and taurine level had varying degrees of changes in alcohol model. From paraffin sections, tissue damage was observed in liver and colon. These findings provide direct evidence that alcohol intake affects the composition of GM, enable a better understanding of the function of GM in the microbiota-gut-brain (MGB) axis, and give a new thought for alcohol addiction treatment.

Probiotic supplementation in trained trotter horses: effect on blood clinical pathology data and urine metabolomic assessed in field

The attention of sports community toward probiotic supplementation as a way to promote exercise and training performance, together with good health, has increased in recent years. This has applied also to horses, with promising results. Here, for the first time, we tested a probiotic mix of several strains of live bacteria typically employed for humans to improve the training performance of Standardbred horses in athletic activity. To evaluate its effects on the horse performance, we measured lactate concentration in blood, a translational outcome largely employed for the purpose, combined with the study of hematological and biochemical parameters, together with urine from a metabolomics perspective. The results showed that the probiotic supplementation significantly reduced postexercise blood lactate concentration. The hematological and biochemical parameters, together with urine molecular profile, suggested that a likely mechanism underlying this positive effect was connected to a switch of energy source in muscle from carbohydrates to short-chain fatty acids. Three sulfur-containing molecules differently concentrated in urines in connection to probiotics administration suggested that such switch was linked to sulfur metabolism. NEW & NOTEWORTHY Probiotic supplementation could reduce postexercise blood lactate concentration in Standardbred horses in athletic activity. Blood parameters, together with urine molecular profile, suggest the mechanism underlying this positive effect is connected to a switch of energy source in muscle from carbohydrates to short-chain fatty acids. Sulfur-containing molecules found in urines in connection to probiotics administration suggested that such switch was linked to sulfur metabolism.

Alcohol, microbiome, and their effect on psychiatric disorders

There is accumulating evidence that alcohol consumption and especially alcohol withdrawal increase brain levels of known innate immune signaling molecules and cause neuroinflammation. It has been shown that microbiota play a pivotal role in this process and affect central neurochemistry and behavior. Disruption of or alterations in the intimate cross-talk between microbiome and brain may be a significant factor in many psychiatric disorders. Alterations in the composition of the microbiome, so called dysbiosis, may result in detrimental distortion of microbe-host homeostasis modulating the hypothalamic-pituitary-adrenal axis. A variety of pathologies are associated with changes in the community structure and function of the gut microbiota, suggesting a link between dysbiosis and disease etiology, including irritable bowel syndrome depression, anxiety disorders, schizophrenia, and alcoholism. Despite a paucity of clinical studies in alcohol-dependent humans, emerging data suggests that alcohol induced alterations of the microbiome may explain reward-seeking behaviors as well as anxiety, depression, and craving in withdrawal and increase the risk of developing psychiatric disorders.

Concurrent gut transcriptome and microbiota profiling following chronic ethanol consumption in nonhuman primates

Alcohol use disorder (AUD) results in increased intestinal permeability, nutrient malabsorption, and increased risk of colorectal cancer (CRC). Our understanding of the mechanisms underlying these morbidities remains limited because studies to date have relied almost exclusively on short-term heavy/binge drinking rodent models and colonic biopsies/fecal samples collected from AUD subjects with alcoholic liver disease (ALD). Consequently, the dose- and site-dependent impact of chronic alcohol consumption in the absence of overt liver disease remains poorly understood. In this study, we addressed this knowledge gap using a nonhuman primate model of voluntary ethanol self-administration where rhesus macaques consume varying amounts of 4% ethanol in water for 12 months. Specifically, we performed RNA-Seq and 16S rRNA gene sequencing on duodenum, jejunum, ileum, and colon biopsies collected from 4 controls and 8 ethanol-consuming male macaques. Our analysis revealed that chronic ethanol consumption leads to changes in the expression of genes involved in protein trafficking, metabolism, inflammation, and CRC development. Additionally, we observed differences in the relative abundance of putatively beneficial bacteria as well as those associated with inflammation and CRC. Given that the animals studied in this manuscript did not exhibit signs of ALD or CRC, our data suggest that alterations in gene expression and bacterial communities precede clinical disease and could serve as biomarkers as well as facilitate future studies aimed at developing interventions to restore gut homeostasis.

The gut-liver axis and the intersection with the microbiome

In the past decade, an exciting realization has been that diverse liver diseases - ranging from nonalcoholic steatohepatitis, alcoholic steatohepatitis and cirrhosis to hepatocellular carcinoma - fall along a spectrum. Work on the biology of the gut-liver axis has assisted in understanding the basic biology of both alcoholic fatty liver disease and nonalcoholic fatty liver disease (NAFLD). Of immense importance is the advancement in understanding the role of the microbiome, driven by high-throughput DNA sequencing and improved computational techniques that enable the complexity of the microbiome to be interrogated, together with improved experimental designs. Here, we review gut-liver communications in liver disease, exploring the molecular, genetic and microbiome relationships and discussing prospects for exploiting the microbiome to determine liver disease stage and to predict the effects of pharmaceutical, dietary and other interventions at a population and individual level. Although much work remains to be done in understanding the relationship between the microbiome and liver disease, rapid progress towards clinical applications is being made, especially in study designs that complement human intervention studies with mechanistic work in mice that have been humanized in multiple respects, including the genetic, immunological and microbiome characteristics of individual patients. These 'avatar mice' could be especially useful for guiding new microbiome-based or microbiome-informed therapies.

Using glycolysis enzyme sequences to inform Lactobacillus phylogeny

The genus Lactobacillus encompasses a diversity of species that occur widely in nature and encode a plethora of metabolic pathways reflecting their adaptation to various ecological niches, including humans, animals, plants and food products. Accordingly, their functional attributes have been exploited industrially and several strains are commonly formulated as probiotics or starter cultures in the food industry. Although divergent evolutionary processes have yielded the acquisition and evolution of specialized functionalities, all Lactobacillus species share a small set of core metabolic properties, including the glycolysis pathway. Thus, the sequences of glycolytic enzymes afford a means to establish phylogenetic groups with the potential to discern species that are too closely related from a 16S rRNA standpoint. Here, we identified and extracted glycolysis enzyme sequences from 52 species, and carried out individual and concatenated phylogenetic analyses. We show that a glycolysis-based phylogenetic tree can robustly segregate lactobacilli into distinct clusters and discern very closely related species. We also compare and contrast evolutionary patterns with genome-wide features and transcriptomic patterns, reflecting genomic drift trends. Overall, results suggest that glycolytic enzymes provide valuable phylogenetic insights and may constitute practical targets for evolutionary studies.

Lactobacillus plantarum prevents and mitigates alcohol-induced disruption of colonic epithelial tight junctions, endotoxemia, and liver damage by an EGF receptor-dependent mechanism

Pathogenesis of alcohol-related diseases such as alcoholic hepatitis involves gut barrier dysfunction, endotoxemia, and toxin-mediated cellular injury. Here we show that Lactobacillus plantarum not only blocks but also mitigates ethanol (EtOH)-induced gut and liver damage in mice. L. plantarum blocks EtOH-induced protein thiol oxidation, and down-regulation of antioxidant gene expression in colon L. plantarum also blocks EtOH-induced expression of TNF-α, IL-1β, IL-6, monocyte chemotactic protein 1 ( MCP1), C-X-C motif chemokine ligand ( CXCL)1, and CXCL2 genes in colon. Epidermal growth factor receptor (EGFR) signaling mediates the L. plantarum-mediated protection of tight junctions (TJs) and barrier function from acetaldehyde, the EtOH metabolite, in Caco-2 cell monolayers. In mice, doxycycline-mediated expression of dominant negative EGFR blocks L. plantarum-mediated prevention of EtOH-induced TJ disruption, mucosal barrier dysfunction, oxidative stress, and inflammatory response in colon. L. plantarum blocks EtOH-induced endotoxemia as well as EtOH-induced pathologic lesions, triglyceride deposition, oxidative stress, and inflammatory responses in the liver by an EGFR-dependent mechanism. L. plantarum treatment after injury accelerated recovery from EtOH-induced TJ, barrier dysfunction, oxidative stress, and inflammatory response in colon, endotoxemia, and liver damage. Results demonstrate that L. plantarum has both preventive and therapeutic values in treatment of alcohol-induced tissue injury, particularly in alcoholic hepatitis.-Shukla, P. K., Meena, A. S., Manda, B., Gomes-Solecki, M., Dietrich, P., Dragatsis, I., Rao, R. Lactobacillus plantarum prevents and mitigates alcohol-induced disruption of colonic epithelial tight junctions, endotoxemia, and liver damage by an EGF receptor-dependent mechanism.