The gut-liver axis

Comprehensive bibliometric and visualized analysis of research on gut-liver axis published from 1998 to 2022

Background

The concept of the gut-liver axis was proposed by Marshall in 1998, and since then, this hypothesis has been gradually accepted by the academic community. Many publications have been published on the gut-liver axis, making it important to assess the scientific implications of these studies and the trends in this field.

Methods

Publications were retrieved from the Web of Science Core Collection. Microsoft Excel, CiteSpace, VOSviewer, and Scimago Graphica software were used for bibliometric analysis.

Results

A total of 776 publications from the Web of Science core database were included in this study. In the past 25 years, the number of publications on the gut-liver axis has shown an upward trend, particularly in the past 3 years (2020-2022). China had the highest number of publications (267 articles, 34.4%). However, the United States was at the top regarding influence and international cooperation in this field. The University of California San Diego had contributed the most publications. Suk, Ki Tae and Schnabl, Bernd were tied for the first rank in most publications. Thematic hotspots and frontiers were focused on gut microbiota, microbial metabolite, intestinal permeability, bacterial translocation, bile acid, non-alcoholic steatohepatitis, and alcoholic liver disease.

Conclusion

Our study is the first bibliometric analysis of literature using visualization software to present the current research status of the gut-liver axis over the past 25 years. The damage and repair of intestinal barrier function, as well as the disruption of gut microbiota and host metabolism, should be a focus of attention. This study can provide a reference for later researchers to understand the global research trends, hotspots, and frontiers in this field.

Comparative efficacy of sequential treatment and open abdomen approaches for corrosive abdominal hemorrhage due to inadequate drainage of duodenal leakage: a cohort study

BACKGROUND

Intra-abdominal bleeding resulting from inadequate drainage of duodenal leakage (DL) is typically caused by the corrosiveness of duodenal fluid. Open abdomen (OA) treatment addresses both the drainage and bleeding simultaneously. However, a sequential treatment (ST) approach involving hemostasis through transcatheter arterial embolization (TAE) followed by percutaneous drainage of source control has emerged as an alternative method. This study aimed to evaluate the prognosis of ST in cases of DL-induced intra-abdominal bleeding.

METHODS

This retrospective cohort study included 151 participants diagnosed with DL-induced intra-abdominal bleeding from January 2004 to December 2010, and January 2013 to December 2021. The ST and OA groups were established based on the treatment method applied. Propensity score-matching (PSM) matched patients in the ST group with those in the OA group.

RESULTS

Among the 151 patients, 61 (40.4%) died within 90 days after the bleeding episode. ST was associated with a lower mortality rate (28.2% vs. 51.3% adjusted odds ratio [OR] = 0.34; 95% confidence interval [CI] 0.17-0.68; P = 0.003) compared to OA. Following PSM, ST remained the only factor associated with reduced mortality (OR = 0.32; 95% CI 0.13-0.75; P = 0.009). Moreover, ST demonstrated a higher rate of initial hemostasis success before (90.1% [64/71] vs. 77.5% [62/80]; adjusted OR = 2.84; 95% CI 1.07-7.60; P = 0.04) and after PSM (94.4% [51/54] vs. 77.8% [42/54], adjusted OR = 3.85; 95% CI 2.15-16.82; P = 0.04). Additionally, ST was associated with a lower incidence of rebleeding within 90 days after the initial bleeding, before (7 vs. 23; adjusted OR 0.41; 95% CI 0.18-0.92; P = 0.03) and after PSM (5 vs. 14; adjusted OR 0.37; 95% CI 0.15-0.93; P = 0.03).

CONCLUSIONS

Applying ST involving TAE and subsequent percutaneous drainage might be superior to OA in lowering the mortality in DL-induced intra-abdominal hemorrhage.

Impacts of prothioconazole and prothioconazole-desthio on bile acid and glucolipid metabolism: Upregulation of CYP7A1 expression in HepG2 cells

As an efficient triazole fungicide, prothioconazole (PTC) is widely used for the prevention and control of plant fungal pathogens. It was reported that the residues of PTC and prothioconazole-desthio (PTC-d) have been detected in the environment and crops, and the effects of PTC-d may be higher than that of PTC. Currently, PTC and PTC-d have been proven to induce hepatic metabolic disorders. However, their toxic effects on cellular bile acid (BA) and glucolipid metabolism remain unknown. In this study, HepG2 cells were exposed to 1-500 μM of PTC or PTC-d. High concentrations of PTC and PTC-d were found to induce cytotoxicity; thus, subsequent experimental exposure was conducted at concentrations of 10-50 μM. The expression levels of CYP7A1 and TG synthesis-related genes and levels of TG and total BA were observed to increase in HepG2 cells. Molecular docking analysis revealed direct interactions between PTC or PTC-d and CYP7A1 protein. To further investigate the underlying mechanisms, PTC and PTC-d were treated to HepG2 cells in which CYP7A1 expression was knocked down using siCYP7A1. It was observed that PTC and PTC-d affected the BA metabolism process and regulated the glycolipid metabolism process by promoting the expression of CYP7A1. In summary, we comprehensively analyzed the effects and mechanisms of PTC and PTC-d on cellular metabolism in HepG2 cells, providing theoretical data for evaluating the safety and potential risks associated with these substances.

Synergistic Effect of Diet and Physical Activity on a NAFLD Cohort: Metabolomics Profile and Clinical Variable Evaluation

Together with its comorbidities, nonalcoholic fatty liver disease (NAFLD) is likely to rise further with the obesity epidemic. However, the literature's evidence shows how its progression can be reduced by the administration of calorie-restrictive dietary interventions and physical activity regimens. The liver function and the gut microbiota have been demonstrated to be closely related. With the aim of ascertaining the impact of a treatment based on the combination of diet and physical activity (versus physical activity alone), we recruited 46 NAFLD patients who were divided into two groups. As a result, we traced the connection between volatile organic compounds (VOCs) from fecal metabolomics and a set of statistically filtered clinical variables. Additionally, we identified the relative abundances of gut microbiota taxa obtained from 16S rRNA gene sequencing. Statistically significant correlations emerged between VOCs and clinical parameters, as well as between VOCs and gut microbiota taxa. In comparison with a physical activity regimen alone, we disclose how ethyl valerate and pentanoic acid butyl ester, methyl valerate, and 5-hepten-2-one, 6-methyl changed because of the positive synergistic effect exerted by the combination of the Mediterranean diet and physical activity regimens. Moreover, 5-hepten-2-one, 6-methyl positively correlated with Sanguinobacteroides, as well as the two genera Oscillospiraceae-UCG002 and Ruminococcaceae UCG010 genera.

C-Type Lectin Receptors-Triggered Antifungal Immunity May Synergize with and Optimize the Effects of Immunotherapy in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors of the digestive system worldwide, and there is a lack of effective treatment for late-stage HCC. Recent experimental studies have demonstrated that dysfunction of the intestinal flora has a significant impact on hepatocarcinogenesis. The pathophysiological link between the intestine, its microbiota, and the liver has been described as the "gut-liver axis". Dysbiosis of the intestinal flora and increased permeability of the intestinal wall are closely associated with liver pathology through the immune response. The "gut-liver axis" theory has been applied to the clinical study of the pathogenesis and treatment of HCC. The intestinal fungal community, as part of the gut microbiome, has a significant impact on human health and disease, while relatively little research has been done in HCC. In this study, we performed a comprehensive analysis of the expression and potential biological functions of the fungal recognition receptors C-type lectin receptors (CLRs) (Dectin-1, Dectin-2, Dectin-3, and Mincle) in HCC. We found that CLRs were downregulated in HCC, and their expressions were correlated with the clinical prognosis of HCC patients. Further studies suggested that the expression of CLRs were significantly correlated with immune infiltration and immunotherapy efficacy in HCC. Based on previous studies and our findings, we hypothesize that intestinal fungal communities and CLRs-triggered antifungal immunity have a key role in the pathogenesis of HCC, and these findings may provide new perspectives and targets for HCC immunotherapy.

The gut–microbiota–brain changes across the liver disease spectrum

Gut microbiota dysbiosis plays a significant role in the progression of liver disease, and no effective drugs are available for the full spectrum. In this study, we aimed to explore the dynamic changes of gut microbiota along the liver disease spectrum, together with the changes in cognition and brain metabolism. Sprague–Dawley rats were divided into four groups reflecting different stages of liver disease: control diet (NC); high-fat, high-cholesterol diet (HFHC), emulating non-alcoholic steatohepatitis; control diet + thioacetamide (NC + TAA), simulating acute liver failure; and high-fat, high-cholesterol diet + thioacetamide (HFHC + TAA) to assess the effect of the superimposed damages. The diet was administered for 14 weeks and the thioacetamide was administrated (100 mg/kg day) intraperitoneally over 3 days. Our results showed changes in plasma biochemistry and liver damage across the spectrum. Differences in gut microbiota at the compositional level were found among the experimental groups. Members of the Enterobacteriaceae family were most abundant in HFHC and HFHC + TAA groups, and Akkermansiaceae in the NC + TAA group, albeit lactobacilli genus being dominant in the NC group. Moreover, harm to the liver affected the diversity and bacterial community structure, with a loss of rare species. Indeed, the superimposed damage group (HFHC + TAA) suffered a loss of both rare and abundant species. Behavioral evaluation has shown that HFHC, NC + TAA, and HFHC + TAA displayed a worsened execution when discriminating the new object. Also, NC + TAA and HFHC + TAA were not capable of recognizing the changes in place of the object. Furthermore, working memory was affected in HFHC and HFHC + TAA groups, whereas the NC + TAA group displayed a significant delay in the acquisition. Brain oxidative metabolism changes were observed in the prefrontal, retrosplenial, and perirhinal cortices, as well as the amygdala and mammillary bodies. Besides, groups administered with thioacetamide presented an increased oxidative metabolic activity in the adrenal glands. These results highlight the importance of cross-comparison along the liver spectrum to understand the different gut–microbiota–brain changes. Furthermore, our data point out specific gut microbiota targets to design more effective treatments, though the liver–gut–brain axis focused on specific stages of liver disease.

A new single-cell protein from Clostridium autoethanogenum as a functional protein for largemouth bass (Micropterus salmoides)

Clostridium autoethanogenum protein (CAP) is a new single-cell protein source originating from inactivated bacteria. An in vitro digestion experiment and an 8-wk growth experiment were conducted to evaluate the molecular weight distribution of the CAP hydrolysate, and the effects of dietary CAP levels on the growth performance, plasma parameters, hepatic and intestinal health, and the diversity of gut-adherent microbiota of largemouth bass (Micropterus salmoides). The fish (initial body weight of 47.99 ± 0.01 g) were fed diets where CAP gradually replaced 0% (CAP0), 12.5% (CAP12.5), 25% (CAP25), 37.5% (CAP37.5) and 50% (CAP50) of low-temperature steam dried anchovy fish meal (LTFM) in the diet. Results showed that the content of peptides below 1,000 Da in the CAP hydrolysate (0.56 mg/mL) was higher than that of the LTFM hydrolysate (0.48 mg/mL). Dietary CAP inclusion had no negative effect on growth performance, while whole-body lipid content significantly reduced in the CAP25 and CAP50 groups (P < 0.05). The plasma alanine aminotransferase activities and triglyceride concentrations in the CAP inclusion groups were significantly lower than those in the CAP0 group (P < 0.05). The plasma aspartate aminotransferase activity was significantly reduced in the CAP37.5 group (P < 0.05). The richness and diversity of the gut-adhesive microbiota and the proportion of Clostridium sensu stricto 12 in the CAP50 group were significantly higher than those in the CAP0 group (P < 0.05). Dietary CAP inclusion inhibited inflammatory responses by down-regulating the mRNA levels of interleukin 1β (IL1β), IL10 and transforming growth factor β1 (P < 0.05) in the liver. The mRNA levels of acetyl-CoA carboxylase 1 were significantly down-regulated in the CAP12.5, CAP25 and CAP37.5 groups (P < 0.05), while that of fatty acid synthase was significantly down-regulated in the CAP50 group (P < 0.05). These results demonstrate that dietary CAP inclusion could improve the hepatic and intestinal health of largemouth bass, and can be helpful to further develop CAP as a functional feed ingredient.

Metabolomic Characteristics of Liver and Cecum Contents in High-Fat-Diet-Induced Obese Mice Intervened with Lactobacillus plantarum FRT10

Obesity has become a major social problem related to health and quality of life. Our previous work demonstrated that Lactobacillus plantarum FRT10 alleviated obesity in high-fat diet (HFD)-fed mice by alleviating gut dysbiosis. However, the underlying functions of FRT10 in regulating liver and cecum contents metabolism remain unknown. Liver and cecum contents metabonomics combined with pathway analysis based on ultraperformance liquid chromatography-quadrupole-time-of-flight mass spectrometry (UHPLC-Q-TOF/MS) were performed to evaluate the alterations of metabolic profiles between obese control mice and obese mice in FRT10-treated groups. The orthogonal partial least squares discriminant analysis (OPLS-DA) score plots showed that there were significant differences in cecum contents and liver markers between experimental groups. In total, 26 potential biomarkers were identified in the liver and 15 in cecum contents that could explain the effect of FRT10 addition in HFD-fed mice. In addition, gut–liver axis analysis indicated that there was a strong correlation between cecum contents metabolites and hepatic metabolites. The mechanism of FRT10 against obesity might be related to the alterations in glycerophospholipid metabolism, primary bile acid biosynthesis, amino metabolism, and purine and pyrimidine metabolism. Studies on these metabolites could help us better understand the role of FRT10 in obesity induced by HFD.

Emerging Role of Edible Exosomes-Like Nanoparticles (ELNs) as Hepatoprotective Agents

Liver diseases are responsible for over 2 million deaths each year and the number is rapidly increasing. There is a strong link between edibles, gut microbiota, liver fat and the liver damage. There are very limited therapeutic options for treatment specifically for Alcoholic liver disease (ALD) and Non-Alcoholic liver disease (NAFLD). Recently, identified Edible Exosomes-like nanoparticles (ELNs) are plant derived membrane bound particles, released by microvesicular bodies for cellular communication and regulate immune responses against many pathogens. Many studies have identified their role as hepatoprotective agent as they carry bioactive material as cargoes which are transferred to recipient cells and affect various biological functions in liver. They are also known to carry specific miRNA, which increases the copy number of beneficial bacteria and the production of lactic acid metabolites in gut and hence restrains from liver injury through portal vein. Few in-vitro studies also have been reported about the anti-inflammatory, anti-oxidant and detoxification properties of ELNs which again protects the liver. The properties such as small size, biocompatibility, stability, low toxicity and non-immunogenicity make ELNs as a better therapeutic option. But, till now, studies on the effect of ELNs as therapeutics are still at its infancy yet promising. Here we discuss about the isolation, characterization, their role in maintaining the gut microbiome and liver homeostasis. Also, we give an outline about the latest advances in ELNs modifications, its biological effects, limitations and we propose the future prospective of ELNs as therapeutics.

Machine learning approach identifies meconium metabolites as potential biomarkers of neonatal hyperbilirubinemia

Background

The gut microbiota plays an important role in the early stages of human life. Our previous study showed that the abundance of intestinal flora involved in galactose metabolism was altered and correlated with increased serum bilirubin levels in children with jaundice. We conducted the present study to systematically evaluate alterations in the meconium metabolome of neonates with jaundice and search for metabolic markers associated with neonatal jaundice.

Methods

We included 68 neonates with neonatal hyperbilirubinemia, also known as neonatal jaundice (NJ) and 68 matched healthy controls (HC), collected meconium samples from them at birth, and performed metabolomic analysis via liquid chromatography-mass spectrometry.

Results

Gut metabolites enabled clearly distinguishing the neonatal jaundice (NJ) and healthy control (HC) groups. We also identified the compositions of the gut metabolites that differed significantly between the NJ and HC groups; these differentially significant metabolites were enriched in aminyl tRNA biosynthesis; pantothenic acid and coenzyme biosynthesis; and the valine, leucine and isoleucine biosynthesis pathways. Gut branched-chain amino acid (BCAA) levels were positively correlated with serum bilirubin levels, and the area under the receiver operating characteristic curve of the random forest classifier model based on BCAAs, proline, methionine, phenylalanine and total bilirubin reached 96.9%, showing good potential for diagnostic applications. Machine learning-based causal inference analysis revealed the causal effect of BCAAs on serum total bilirubin and NJ.

Conclusions

Altered gut metabolites in neonates with jaundice showed that increased BCAAs and total serum bilirubin were positively correlated. BCAAs proline, methionine, phenylalanine are potential biomarkers of NJ.

In vivo effects of Viscum album and probiotics against carbon tetrachloride-induced liver injury

This study tested the possible protective and therapeutic effects of Viscum album extract and probiotics against carbon tetrachloride (CCl₄)-induced acute/chronic liver injury. Male Wistar rats were assigned to seven groups: Control, acute CCl₄, acute V. album + CCl₄, acute V. album + Probiotics + CCl₄, chronic CCl₄, chronic CCl₄ + V. album, and chronic CCl₄ + V. album + Probiotics. Acute and chronic liver injuries were induced by 2 mg/kg CCl₄ (i.p.) and 1 mg/kg CCl₄ (i.p.), respectively. The extract and probiotics were administered daily to related groups. Serum enzyme activities, lipid profile, total protein, albumin, bilirubin, heme oxgenase-1 and 8-hydroxydeoxyguanosine levels were measured. Liver tissue sections stained with Hematoxylin-Eosin. Acute or chronic CCl₄-exposure caused to significant changes in concentrations/activities of the measured parameters. The oral administration of extract and probiotics showed protective and therapeutic effects against CCl₄-induced liver-injury. The supplementation of intestinal flora by the use of probiotics may enhance the efficacy of orally given therapeutic extracts.

Bile Acids and GPBAR-1: Dynamic Interaction Involving Genes, Environment and Gut Microbiome

Bile acids (BA) are amphiphilic molecules synthesized in the liver from cholesterol. BA undergo continuous enterohepatic recycling through intestinal biotransformation by gut microbiome and reabsorption into the portal tract for uptake by hepatocytes. BA are detergent molecules aiding the digestion and absorption of dietary fat and fat-soluble vitamins, but also act as important signaling molecules via the nuclear receptor, farnesoid X receptor (FXR), and the membrane-associated G protein-coupled bile acid receptor 1 (GPBAR-1) in the distal intestine, liver and extra hepatic tissues. The hydrophilic-hydrophobic balance of the BA pool is finely regulated to prevent BA overload and liver injury. By contrast, hydrophilic BA can be hepatoprotective. The ultimate effects of BA-mediated activation of GPBAR-1 is poorly understood, but this receptor may play a role in protecting the remnant liver and in maintaining biliary homeostasis. In addition, GPBAR-1 acts on pathways involved in inflammation, biliary epithelial barrier permeability, BA pool hydrophobicity, and sinusoidal blood flow. Recent evidence suggests that environmental factors influence GPBAR-1 gene expression. Thus, targeting GPBAR-1 might improve liver protection, facilitating beneficial metabolic effects through primary prevention measures. Here, we discuss the complex pathways linked to BA effects, signaling properties of the GPBAR-1, mechanisms of liver damage, gene-environment interactions, and therapeutic aspects.

Gut-Liver Immune Response and Gut Microbiota Profiling Reveal the Pathogenic Mechanisms of Vibrio harveyi in Pearl Gentian Grouper (Epinephelus lanceolatus × E. fuscoguttatus )

Vibrio harveyi causes vibriosis in nearly 70% of grouper (Epinephelus sp.), seriously limiting grouper culture. As well as directly inhibiting pathogens, the gut microbiota plays critical roles in immune homeostasis and provides essential health benefits to its host. However, there is still little information about the variations in the immune response to V. harveyi infection and the gut microbiota of grouper. To understand the virulence mechanism of V. harveyi in the pearl gentian grouper, we investigated the variations in the pathological changes, immune responses, and gut bacterial communities of pearl gentian grouper after exposure to differently virulent V. harveyi strains. Obvious histopathological changes were detected in heart, kidney, and liver. In particular, nodules appeared and huge numbers of V. harveyi cells colonized the liver at 12 h postinfection (hpi) with highly virulent V. harveyi. Although no V. harveyi was detected in the gut, the infection simultaneously induced a gut-liver immune response. In particular, the expression of 8 genes associated with cellular immune processes, including genes encoding inflammatory cytokines and receptors, and pattern recognition proteins, was markedly induced by V. harveyi infection, especially with the highly virulent V. harveyi strain. V. harveyi infection also induced significant changes in gut bacterial community, in which Vibrio and Photobacterium increased but Bradyrhizobium, Lactobacillus, Blautia, and Faecalibaculum decreased in the group infected with the highly virulent strain, with accounting for 82.01% dissimilarity. Correspondingly, four bacterial functions related to bacterial pathogenesis were increased by infection with highly virulent V. harveyi, whereas functions involving metabolism and genetic information processing were reduced. These findings indicate that V. harveyi colonizes the liver and induces a gut-liver immune response that substantially disrupts the composition of and interspecies interactions in the bacterial community in fish gut, thereby altering the gut-microbiota-mediated functions and inducing fish death.

Plant protein diet-induced hypoimmunity by affecting the spiral valve intestinal microbiota and bile acid enterohepatic circulation in Amur sturgeon (Acipenser schrenckii)

An 8-week growth trial was conducted to study enterohepatic recirculation of bile acid metabolism and the intestinal microbiota of Amur sturgeon (Acipenser schrenckii) fed with three diets, including 540 g/kg, 270 g/kg or 0 g/kg fishmeal, which was correspondingly replaced by a plant protein blend (named P0, P50 and P100, respectively). The diets were designed to be isonitrogenous, isoenergetic and essential nutrients balanced. With rising levels of dietary plant protein, disruption of the spiral valve intestinal microbiota and more morbidity with liver disease were observed in the P100 group, although there were no haematological abnormalities observed. An obvious bile acids enterohepatic circulation disorder was found with phenotypes of increased liver bile acids compensatory synthesis, and reduced expression of bile acid receptors (FXR and TGR5), which induced BA accumulative toxicity. Accompanied by increased oxidative stress, it further induced hepatic lesions and hypoimmunity, which were non-negligible reasons for the high mortality and low utilization ability of plant protein by Amur sturgeon.

Diarrhea and elevation of plasma markers of cholestasis are common and often occur concomitantly in critically ill patients

PURPOSE

We aimed to describe epidemiology of diarrhea and cholestasis in critically ill patients and explore associations between these two conditions.

MATERIAL AND METHODS

We performed a retrospective study including all consecutive patients who stayed in the ICU for at least 3 days and in whom plasma measurements of liver enzymes/cholestasis parameters were performed. Diarrhea was defined as 3 or more loose or liquid stools per day and cholestasis as increase of alkaline phosphatase (ALP) and gamma glutamyl transpeptidase (GGT) 1.5 times above the upper limit of normality.

RESULTS

Diarrhea was observed in 26.1% and cholestasis in 27.9% of study patients, about one third of the cases in both diarrhea and cholestasis occurred beyond the first week of patient's ICU stay. Cholestasis occurred in 45.6% of patients with diarrhea vs 28.0% of patients without diarrhea (p < 0.001). In 94 patients (13.1%) both diarrhea and cholestasis occurred, cholestasis was more commonly (2/3 of cases) documented before manifestation of diarrhea.

CONCLUSIONS

Cholestasis is more common in patients with diarrhea and vice versa. Diarrhea and cholestasis both occur in approximately one quarter of ICU patients, with significant proportion manifesting beyond the first week in the ICU.

Perfluorooctane sulfonate alters gut microbiota-host metabolic homeostasis in mice

Perfluorooctane sulfonate (PFOS) is a persistent environmental chemical whose biological effects are mediated by multiple mechanisms. Recent evidence suggests that the gut microbiome may be directly impacted by and/or alter the fate and effects of environmental chemicals in the host. Thus, the aim of this study was to determine whether PFOS influences the gut microbiome and its metabolism, and the host metabolome. Four groups of male C57BL/6 J mice were fed a diet with or without 0.003 %, 0.006 %, or 0.012 % PFOS, respectively. 16S rRNA gene sequencing, metabolomic, and molecular analyses were used to examine the gut microbiota of mice after dietary PFOS exposure. Dietary PFOS exposure caused a marked change in the gut microbiome compared to controls. Dietary PFOS also caused dose-dependent changes in hepatic metabolic pathways including those involved in lipid metabolism, oxidative stress, inflammation, TCA cycle, glucose, and amino acid metabolism. Changes in the metabolome correlated with changes in genes that regulate these pathways. Integrative analyses also demonstrated a strong correlation between the alterations in microbiota composition and host metabolic profiles induced by PFOS. Further, using isolated mouse cecal contents, PFOS exposure directly affected the gut microbiota metabolism. Results from these studies demonstrate that the molecular and biochemical changes induced by PFOS are mediated in part by the gut microbiome, which alters gene expression and the host metabolome in mice.

Gut Microbial Dysbiosis Is Associated With Profibrotic Factors in Liver Fibrosis Mice

Background and Aims: Continuous development will evolve into end-stage liver disease. Profibrotic factors NOX4 and RhoA participate in the activation of HSC and accelerate the development of liver fibrosis. Abnormal intrahepatic metabolism during liver fibrosis interferes with intestinal homeostasis through the liver—gut axis.

Methods: Wild-type (WT), NOX4 knockout, RhoA expression inhibition C57BL/6 mice were randomly divided into 6 groups as follows: control group, CCl₄ group, NOX4^−/− group, AP group, RhoAi group, and FA group.

Results: The results of alpha-diversity suggest that the diversity and abundance of intestinal flora in liver fibrosis mice is lower than that in normal mice, but there is some recovery in liver fibrosis mice with NOX4 or RhoA intervention. The flora structure showed that the intestinal flora of the control group, NOX4^−/− group, AP group, RhoAi group, and FA group belonged to one type, while the intestinal flora of the CCl₄ group belonged to another type. In addition, analysis of the composition of the flora at the level of the phylum and genus also suggested the decline in Firmicutes and Lactobacillus caused by liver fibrosis has partially restore in the liver fibrosis mice with NOX4 or RhoA intervention. In terms of functional prediction, the “Secondary metabolites biosynthesis, transport and catabolism,” “Infectious diseases,” and “Xenobiotics biodegradation and metabolism” signaling pathways are mainly enriched in liver fibrosis mice, and the “Energy production and conversion,” “Defense mechanisms,” and “Carbohydrate metabolism” signaling pathways are mainly enriched in the NOX4 and RhoA intervention groups.

Conclusion: In the case of liver fibrosis, the intestinal flora is disordered, and the disorder is related to NOX4 and RhoA. This study provides theoretical support for a better understanding of the underlying mechanisms of liver fibrosis development.

Gut microbiome: An intermediary to neurotoxicity

There is growing recognition that the gut microbiome is an important regulator for neurological functions. This review provides a summary on the role of gut microbiota in various neurological disorders including neurotoxicity induced by environmental stressors such as drugs, environmental contaminants, and dietary factors. We propose that the gut microbiome remotely senses and regulates CNS signaling through the following mechanisms: 1) intestinal bacteria-mediated biotransformation of neurotoxicants that alters the neuro-reactivity of the parent compounds; 2) altered production of neuro-reactive microbial metabolites following exposure to certain environmental stressors; 3) bi-directional communication within the gut-brain axis to alter the intestinal barrier integrity; and 4) regulation of mucosal immune function. Distinct microbial metabolites may enter systemic circulation and epigenetically reprogram the expression of host genes in the CNS, regulating neuroinflammation, cell survival, or cell death. We will also review the current tools for the study of the gut-brain axis and provide some suggestions to move this field forward in the future.

Tissue Distribution of Active Principles from Alpiniae Oxyphyllae Fructus Extract: An Experimental Study in Rats

Background:

Alpiniae Oxyphyllae Fructus (Yizhi in Chinese) have been widely used as an herbal medicine for the treatment of diuresis, enuresis and diarrhea in China. Many studies have deciphered some potential underlying mechanisms for its anti-diarrheal effects. However, tissue distribution of Yizhi constituents is warranted because pharmacological receptors are frequently located in tissues. Moreover, it is also interesting to know about the potential correlation between behavior in drug distribution and the observed pharmacological response. The aim of this study is to investigate tissue distribution behaviors of Yizhi constituents after oral administration of Yizhi extract to rats, focusing on 10 active principles.

Methods:

Twenty four male Sprague Dawley rats were given orally the Yizhi extract and fourteen tissue samples were collected after being killed by bleeding from the abdominal aorta under ether anesthesia at different time-points. The resulting tissues were excised and homogenized. Based on our previous reports, liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) was used to quantify the target analytes, as well as phase II metabolites, in the various biosamples.

Results:

Almost all the targeted Yizhi active principles and some glucuronidated metabolites were qualitatively measured in rat stomach, small intestine, large intestine, as well as liver. Nootkatone, yakuchinone A and tectochrysin were observed in the rat brain. In other rat tissues, these analytes had lower exposure or could not be detected. Consistently, quantitative analysis revealed that the Yizhi active principles dominantly distributed into gastrointestinal tissues followed by liver, the overall exposure levels ranking as follows: stomach > small intestine > large intestine > liver. Tissue concentrationtime profiles of the test active principles in rat stomach, small intestine, and large intestine were bimodal with two concentration peaks occurring at 0.5 and 4h after oral administration, respectively. The exposure levels in rat kidney and bladder were quite low.

Conclusion:

The active principles of Yizhi were specially distributed into gastrointestinal tissues after oral administration of its ethanol extract to rats. The tissue distribution behaviors partly supported its anti-diarrheal effects from a pharmacokinetic opinion. This paper will be useful as the starting point for studying the pharmacological activities of this traditional herb.

Roles of the inflammasome in the gut‑liver axis (Review)

The gut-liver axis connects the liver with the intestine via bile acid metabolism. Bile acid dysregulation leads to intestinal dysbiosis, that allows enterogenous pathogenic bacteria, including Gram-negative bacteria and their products lipopolysaccharide (LPS), into the liver via the portal vein, triggering inflammation in the liver. The inflammasome serves as an intracellular pattern recognition receptor that detects pathogens or danger signals and mediates innate immunity in the liver or gut. Specifically, the NACHT, LRR and PYD domains-containing protein (NLRP)6 inflammasome maintains intestinal microbial balance, by promoting interleukin (IL)-18-dependent antimicrobial peptide synthesis and mucus secretion from goblet cells. The NLRP3 inflammasome, in contrast, primarily induces IL-1β and aggravates inflammatory liver injury. Furthermore, the NLRP3 inflammasome affects the epithelial integrity of cholangiocytes by inducing the production of pro-inflammatory cytokines. In addition, bile acids, including deoxycholic acid and chenodeoxycholic acid, are able to activate the NLRP3 inflammasome in macrophages; however, bile acids have the potential to exert the opposite role by interacting with the membrane-bound Takeda G-protein receptor 5 or by activating nuclear farnesoid-X receptor. Therefore, further investigation of the molecular mechanisms underlying the inflammasome, involved in the gut-liver axis, may provide important insights into the identification of a potential therapeutic target for the treatment of liver and gut diseases. The present review discusses the roles of the inflammasome in the gut-liver axis, and the emerging associations between the inflammasome and the intestinal microbiota or the bile acids in the gut-liver axis.

Hypoalbuminemia: Pathogenesis and Clinical Significance

Hypoalbuminemia is associated with inflammation. Despite being addressed repeatedly in the literature, there is still confusion regarding its pathogenesis and clinical significance. Inflammation increases capillary permeability and escape of serum albumin, leading to expansion of interstitial space and increasing the distribution volume of albumin. The half‐life of albumin has been shown to shorten, decreasing total albumin mass. These 2 factors lead to hypoalbuminemia despite increased fractional synthesis rates in plasma. Hypoalbuminemia, therefore, results from and reflects the inflammatory state, which interferes with adequate responses to events like surgery or chemotherapy, and is associated with poor quality of life and reduced longevity. Increasing or decreasing serum albumin levels are adequate indicators, respectively, of improvement or deterioration of the clinical state. In the interstitium, albumin acts as the main extracellular scavenger, antioxidative agent, and as supplier of amino acids for cell and matrix synthesis. Albumin infusion has not been shown to diminish fluid requirements, infection rates, and mortality in the intensive care unit, which may imply that there is no body deficit or that the quality of albumin “from the shelf” is unsuitable to play scavenging and antioxidative roles. Management of hypoalbuminaemia should be based on correcting the causes of ongoing inflammation rather than infusion of albumin. After the age of 30 years, muscle mass and function slowly decrease, but this loss is accelerated by comorbidity and associated with decreasing serum albumin levels. Nutrition support cannot fully prevent, but slows down, this chain of events, especially when combined with physical exercise.

Association of serum bilirubin in newborns affected by jaundice with gut microbiota dysbiosis

BACKGROUND AND AIMS

Breast milk jaundice (BMJ) is common and benign, but neonatal cholestasis (NC) is rare and not benign, so early differentiation between NC and non-NC jaundice is important and may facilitate diagnosis and treatment. Gut microbiota plays an important role in enterohepatic circulation, which in turn plays an important role in the secretion of bilirubin. We aimed to determine the composition of gut microbiota in patients with NC and BMJ, and to identify the gut microbiota composition associated with NC and BMJ.

METHODS

Data on age, gender, delivery, feeding mode, serum total bilirubin, direct bilirubin, and liver function were collected for NC patients, BMJ patients and healthy controls, respectively. Shotgun metagenomic sequencing and metagenome-wide association were performed.

RESULTS

Forty NC patients, 16 patients affected by BMJ, and 14 healthy controls (CON) without jaundice were enrolled. A significant increase in species richness, especially Bacteroides, was found in NC patients. The abundances of potentially pathogenic species and KEGG orthologies (KOs) of virulence factor genes were positively correlated with serum bilirubin level. The abundances of nine species of Bifidobacterium and three KOs of galactose metabolism were significantly decreased in the jaundice group (NC and BMJ) and were negatively correlated with serum bilirubin level.

CONCLUSIONS

The gut microbiota in NC patients is characterized by a significant increase in species richness, possibly due to the proliferation of potentially pathogenic species. Additionally, the gut microbiota in jaundice patients is characterized by a decreased abundance of Bifidobacterium. Decreased Bifidobacterium has been associated with elevated bilirubin and abnormal gut microbiota galactose metabolic pathway. Further, ten bacteria species were identified as potential biomarker of jaundice.

KEY POINTS

Question Is there any alteration of gut microbiotain neonatal cholestasis patients? Does gut microbiota have any involvement in the occurrence of neonatal cholestasis or breast milk jaundice? Findings The alteration of gut microbiota in neonatal cholestasis patients mainly manifested as a significant increase in species richness and an increased abundance of potentially pathogenic species, while the main manifestation in jaundice patients was a significant decrease in Bifidobacterium which may be involved in the metabolism of bilirubin through the galactose metabolic pathway. Meaning The results suggest that an imbalance of gut microbiota exist in neonatal cholestasis and breast milk jaundice patients, primarily in the form of a substantial reduction in the abundance of Bifidobacterium, suggesting the possibility of intervention treatment for neonatal cholestasis and breast milk jaundice by supplementing probiotics.

Autoimmune liver disease and the enteric microbiome

The human enteric microbiome is highly complex and has more than 150 times more genes within it than its host. The host and the microbiome have a commensurate relationship that can evolve over time. The typically symbiotic relationship between the two can become pathogenic. The microbiome composition in adults reflects their history of exposure to bacteria and environmental factors during early life, their genetic background, age, interactions with the immune system, geographical location, and, most especially, their diet. Similarly, these factors are thought to contribute to the development of autoimmune disease. It is possible that alterations in the intestinal microbiome could lead to liver disease. There is emerging data for the contribution of the microbiome in development of primary sclerosing cholangitis, primary biliary cholangitis, and autoimmune hepatitis; liver disorders associated with aberrant immune function in genetically susceptible individuals.

Gut : liver : brain axis: the microbial challenge in the hepatic encephalopathy

Hepatic encephalopathy (HE) is a debilitating neuropsychiatric condition often associated with acute liver failure or cirrhosis. Advanced liver diseases are characterized by a leaky gut and systemic inflammation. There is strong evidence that the pathogenesis of HE is linked to a dysbiotic gut microbiota and to harmful microbial by-products, such as ammonia, indoles, oxindoles and endotoxins. Increased concentrations of these toxic metabolites together with the inability of the diseased liver to clear such products is thought to play an important patho-ethiological role. Current first line clinical treatments target microbiota dysbiosis by decreasing the counts of pathogenic bacteria, blood endotoxemia and ammonia levels. This review will focus on the role of the gut microbiota and its metabolism in HE and advanced cirrhosis. It will critically assess data from different clinical trials measuring the efficacy of the prebiotic lactulose, the probiotic VSL#3 and the antibiotic rifaximin in treating HE and advanced cirrhosis, through gut microbiota modulation. Additionally data from Randomised Controlled Trials using pre-, pro- and synbiotic will be also considered by reporting meta-analysis studies. The large amount of existing data showed that HE is a clear example of how an altered gut microbiota homeostasis can influence and impact on physiological functions outside the intestine, with implication for host health at the systems level. Nevertheless, a strong effort should be made to increase the information on gut microbiota ecology and its metabolic function in liver diseases and HE.

Effect of Liraglutide Treatment on Jejunostomy Output in Patients With Short Bowel Syndrome: An Open-Label Pilot Study

BACKGROUND

An impaired hormonal "ileo-colonic brake" may contribute to rapid gastric emptying, gastric hypersecretion, high ostomy losses, and the need for parenteral support in end-jejunostomy short bowel syndrome (SBS) patients with intestinal failure (IF). Liraglutide, a glucagon-like peptide 1 receptor agonist, may reduce gastric hypersecretion and dampen gastric emptying, thereby improving conditions for intestinal absorption.

MATERIALS AND METHODS

In an 8-week, open-label pilot study, liraglutide was given subcutaneously once daily to 8 end-jejunostomy patients, aged 63.4 ± 10.9 years (mean ± SD) and with small bowel lengths of 110 ± 66 cm. The 72-hour metabolic balance studies were performed before and at the end of treatment. Food intake was unrestricted. Oral fluid intake and parenteral support volume were kept constant. The primary end point was change in the ostomy wet weight output.

RESULTS

Liraglutide reduced ostomy wet weight output by 474 ± 563 g/d from 3249 ± 1352 to 2775 ± 1187 g/d (P = .049, Student t test). Intestinal wet weight absorption tended to increase by 464 ± 557 g/d (P = .05), as did urine production by 765 ± 759 g/d (P = .02). Intestinal energy absorption improved by 902 ± 882 kJ/d (P = .02).

CONCLUSION

Liraglutide reduced ostomy wet weight output in end-jejunostomy patients with SBS-IF and increased their intestinal wet weight and energy absorption. If larger, randomized, placebo-controlled studies confirm these effects, it adds to the hypothesis that many ileo-colonic brake hormones in conjunction may be involved in the process of intestinal adaptation. By identification of key hormones and addressing their potential synergistic effects, better treatments may be provided to patients with SBS-IF. This trial was registered at clinicaltrialsregister.eu as 2013-005499-16.

Alterations and correlations of the gut microbiome, metabolism and immunity in patients with primary biliary cirrhosis

We selected 42 early-stage primary biliary cirrhosis (PBC) patients and 30 healthy controls (HC). Metagenomic sequencing of the 16S rRNA gene was used to characterize the fecal microbiome. UPLC-MS/MS assaying of small molecules was used to characterize the metabolomes of the serum, urine and feces. Liquid chip assaying of serum cytokines was used to characterize the immune profiles. The gut of PBC patients were depleted of some potentially beneficial bacteria, such as Acidobacteria, Lachnobacterium sp., Bacteroides eggerthii and Ruminococcus bromii, but were enriched in some bacterial taxa containing opportunistic pathogens, such as γ-Proteobacteria, Enterobacteriaceae, Neisseriaceae, Spirochaetaceae, Veillonella, Streptococcus, Klebsiella, Actinobacillus pleuropneumoniae, Anaeroglobus geminatus, Enterobacter asburiae, Haemophilus parainfluenzae, Megasphaera micronuciformis and Paraprevotella clara. Several altered gut bacterial taxa exhibited potential interactions with PBC through their associations with altered metabolism, immunity and liver function indicators, such as those of Klebsiella with IL-2A and Neisseriaceae with urinary indoleacrylate. Many gut bacteria, such as some members of Bacteroides, were altered in their associations with the immunity and metabolism of PBC patients, although their relative abundances were unchanged. Consequently, the gut microbiome is altered and may be critical for the onset or development of PBC by interacting with metabolism and immunity.

Alcohol extract of North American ginseng (Panax quinquefolius) reduces fatty liver, dyslipidemia, and other complications of metabolic syndrome in a mouse model

We investigated whether North American ginseng (Panax quinquefolius) could reduce development of the metabolic syndrome phenotype in a mouse model (ETKO) of the disease. Young ETKO mice have no disease but similar to humans start to develop the fatty liver, hypertriglyceridemia, obesity, and insulin resistance at 25-30 weeks of age, and the disease continues to progress with ageing. ETKO mice were orally given an ethanol extract of ginseng roots at 4 and 32 weeks of age. Treatments with ginseng eliminated the ETKO fatty liver, reduced hepatic and intestinal lipoprotein secretion, and reduced the level of circulating lipids. Improvements by ginseng treatments were manifested as a reduction in the expression of genes involved in the regulation of fatty acid and triglyceride (fat) synthesis and secretion by the lipoproteins on one hand, and the stimulation of fatty acid oxidation and triglyceride degradation by lipolysis on the other hand. These processes altogether improved glucose, fatty acid, and triglyceride metabolism, reduced liver fat load, and reversed the progression of metabolic syndrome. These data confirm that treatments with North American ginseng could alleviate metabolic syndrome through the maintenance of a better balance between glucose and fatty acid metabolism, lipoprotein secretion, and energy homeostasis in disease-prone states.

Saccharomyces boulardii Administration Changes Gut Microbiota and Attenuates D-Galactosamine-Induced Liver Injury

Growing evidence has shown that gut microbiome is a key factor involved in liver health. Therefore, gut microbiota modulation with probiotic bacteria, such as Saccharomyces boulardii, constitutes a promising therapy for hepatosis. In this study, we aimed to investigate the protective effects of S. boulardii on D-Galactosamine-induced liver injury in mice. Liver function test and histopathological analysis both suggested that the liver injury can be effectively attenuated by S. boulardii administration. In the meantime, S. boulardii induced dramatic changes in the gut microbial composition. At the phylum level, we found that S. boulardii significantly increased in the relative abundance of Bacteroidetes, and decreased the relative abundance of Firmicutes and Proteobacteria, which may explain the hepatic protective effects of S. boulardii. Taken together, our results demonstrated that S. boulardii administration could change the gut microbiota in mice and alleviate acute liver failure, indicating a potential protective and therapeutic role of S. boulardii.

Drug-induced liver injury: Do we know everything?

Interest in drug-induced liver injury (DILI) has dramatically increased over the past decade, and it has become a hot topic for clinicians, academics, pharmaceutical companies and regulatory bodies. By investigating the current state of the art, the latest scientific findings, controversies, and guidelines, this review will attempt to answer the question: Do we know everything? Since the first descriptions of hepatotoxicity over 70 years ago, more than 1000 drugs have been identified to date, however, much of our knowledge of diagnostic and pathophysiologic principles remains unchanged. Clinically ranging from asymptomatic transaminitis and acute or chronic hepatitis, to acute liver failure, DILI remains a leading causes of emergent liver transplant. The consumption of unregulated herbal and dietary supplements has introduced new challenges in epidemiological assessment and clinician management. As such, numerous registries have been created, including the United States Drug-Induced Liver Injury Network, to further our understanding of all aspects of DILI. The launch of LiverTox and other online hepatotoxicity resources has increased our awareness of DILI. In 2013, the first guidelines for the diagnosis and management of DILI, were offered by the Practice Parameters Committee of the American College of Gastroenterology, and along with the identification of risk factors and predictors of injury, novel mechanisms of injury, refined causality assessment tools, and targeted treatment options have come to define the current state of the art, however, gaps in our knowledge still undoubtedly remain.

Remote Sensing between Liver and Intestine: Importance of Microbial Metabolites

Recent technological advancements including metagenomics sequencing and metabolomics have allowed the discovery of critical functions of gut microbiota in obesity, malnutrition, neurological disorders, asthma, and xenobiotic metabolism. Classification of the human gut microbiome into distinct "enterotypes" has been proposed to serve as a new paradigm for understanding the interplay between microbial variation and human disease phenotypes, as many organs are affected by gut microbiota modifications during the pathogenesis of diseases. Gut microbiota remotely interacts with liver and other metabolic organs of the host through various microbial metabolites that are absorbed into the systemic circulation.

PURPOSE OF REVIEW

The present review summarizes recent literature regarding the importance of gut microbiota in modulating the physiological and pathological responses of various host organs, and describes the functions of the known microbial metabolites that are involved in this remote sensing process, with a primary focus on the gut microbiota-liver axis.

RECENT FINDINGS

Under physiological conditions, gut microbiota modulates the hepatic transcriptome, proteome, and metabolome, most notably down-regulating cytochrome P450 3a mediated xenobiotic metabolism. Gut microbiome also modulates the rhythmicity in liver gene expression, likely through microbial metabolites, such as butyrate and propionate that serve as epigenetic modifiers. Additionally, the production of host hormones such as primary bile acids and glucagon like peptide 1 is altered by gut microbiota to modify intermediary metabolism of the host.

SUMMARY

Dysregulation of gut microbiota is implicated in various liver diseases such as alcoholic liver disease, non-alcoholic steatohepatitis, liver cirrhosis, cholangitis, and liver cancer. Gut microbiota modifiers such as probiotics and prebiotics are increasingly recognized as novel therapeutic modalities for liver and other types of human diseases.

Is it enough to eliminate hepatitis C virus to reverse the damage caused by the infection?

Hepatitis C virus (HCV) infection represents one of the major causes of chronic liver disease, hepatocellular carcinoma and morbidity/mortality worldwide. It is also a major burden to the healthcare systems. A complete elimination of the HCV from the body through treatment is now possible. However, HCV not only alters the hepatic function. Several extra-hepatic manifestations are present in HCV-infected patients, which increase the mortality rate. Liver and gut are closely associated in what is called the “gut-liver axis”. A disrupted gut barrier leads to an increase in bacterial translocation and an activation of the mucosal immune system and secretion of inflammatory mediators that plays a key role in the progression of liver disease towards decompensated cirrhosis in HCV-infected patients. In addition, both qualitative and quantitative changes in the composition of the gut microbiota (GM) and states of chronic inflammation have been observed in patients with cirrhosis. Thus, a successful treatment of HCV infection should be also accompanied by a complete restoration of GM composition in order to avoid activation of the mucosal immune system, persistent inflammation and the development of long-term complications. Evaluation of GM composition after treatment could be of interest as a reliable indicator of the total or partial cure of these patients. However, studies focused on microbiota composition after HCV eradication from the body are lacking, which opens unique opportunities to deeply explore and investigate this exciting field.

Intestinal injury in the rat model of 17α-ethynylestradiol-induced intrahepatic cholestasis

OBJECTIVE

Although the intimate relationship between liver and gut has been previously reported under physiological and pathological conditions, intestinal involvement in the process of intrahepatic cholestasis of pregnancy remains unclear. The aim of this study was to investigate intestinal changes in 17α-ethynylestradiol (EE)-induced cholestatic rat model.

METHODS

Liver injury was assessed by HE stain and serum biochemical parameters were measured. Intestinal transit was determined using ink marks. Neuronal protein expressions in the intestine were analyzed by Western blot.

RESULTS

EE treatment induced liver damage, including severe bile duct hyperplasia, portal edema, portal infiltration, a loss of hepatic structure in periportal areas and increased serum levels of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase and total bilirubin. Large areas of inflammatory cell infiltration and increased myeloperoxidase activity were observed in the intestine of EE-induced cholestatic rats. The EE-treated group showed increased intestinal transit and malondialdehyde levels, while the glutathione content and superoxide dismutase activity were notably decreased, together with decreased protein gene product 9.5 and neuronal nitric oxide synthase expression in the ileum and colon. Furthermore, choline acetyltransferase expression was significantly decreased in the ileum, whereas no change was observed in the colon of EE-treated rats.

CONCLUSION

EE-induced liver damage is associated with oxidative stress, inflammation and neural loss in the intestine, which may lead to altered intestinal motility.

Effects of Salmonella infection on hepatic damage following acute liver injury in rats

BACKGROUND

Acute liver injury is a common clinical disorder associated with intestinal barrier injury and disturbance of intestinal microbiota. Probiotic supplementation has been reported to reduce liver injury; however, it is unclear whether enteropathogen infection exacerbates liver injury. The purpose of this study was to address this unanswered question using a rat model.

METHODS

Oral supplementation with Salmonella enterica serovar enteritidis (S. enteritidis) was given to rats for 7 days. Different degrees of acute liver injury were then induced by intraperitoneal injection of D-galactosamine. The presence and extent of liver injury was assayed by measuring the concentrations of serum alanine aminotransferase, aspartate aminotransferase, and total bilirubin. Histology was used to observe liver tissue damage. Additionally, we measured the changes in plasma endotoxin, serum cytokines and bacterial translocation to clarify the mechanisms underlying intestinal microbiota associated liver injury.

RESULTS

The levels of liver damage and endotoxin were significantly increased in the Salmonella infected rats with severe liver injury compared with the no infection rats with severe liver injury (P<0.01); The peyer's patch CD3+ T cell counts were increased significantly when the Salmonella infection with severe injury group was compared with the normal group (P<0.05). S. enteritidis pretreatment enhanced intestinal barrier impairment and bacterial translocation.

CONCLUSIONS

Oral S. enteritidis administration exacerbates acute liver injury, especially when injury was severe. Major factors of the exacerbation include inflammatory and oxidative stress injuries induced by the translocated bacteria and associated endotoxins, as well as over-activation of the immune system in the intestine and liver.

Oral immune therapy: targeting the systemic immune system via the gut immune system for the treatment of inflammatory bowel disease

Inflammatory bowel diseases (IBD) are associated with an altered systemic immune response leading to inflammation-mediated damage to the gut and other organs. Oral immune therapy is a method of systemic immune modulation via alteration of the gut immune system. It uses the inherit ability of the innate system of the gut to redirect the systemic innate and adaptive immune responses. Oral immune therapy is an attractive clinical approach to treat autoimmune and inflammatory disorders. It can induce immune modulation without immune suppression, has minimal toxicity and is easily administered. Targeting the systemic immune system via the gut immune system can serve as an attractive novel therapeutic method for IBD. This review summarizes the current data and discusses several examples of oral immune therapeutic methods for using the gut immune system to generate signals to reset systemic immunity as a treatment for IBD.

PNPLA3 148M Carriers with Inflammatory Bowel Diseases Have Higher Susceptibility to Hepatic Steatosis and Higher Liver Enzymes

BACKGROUND

Inflammatory bowel diseases (IBD) are characterized by chronic relapsing inflammation of the gastrointestinal tract and encompass Crohn's disease and ulcerative colitis. IBD are often associated with extraintestinal manifestations affecting multiple organs including the liver. Increased levels of serum aminotransferases, possibly related to nonalcoholic fatty liver disease, constitute one of the most frequently described IBD-related liver diseases. The PNPLA3 I148M substitution is a major common genetic determinant of hepatic fat content and progression to chronic liver disease. The aim of this study was to investigate whether carriers of PNPLA3 148M allele with IBD have higher risk of liver steatosis and increase in transaminases levels.

METHODS

The PNPLA3 I148M (rs738409) genotype was performed by Taqman assays in 158 individuals from Southern Italy (namely, Catanzaro cohort) and in 207 individuals from Northern Italy (namely, Milan cohort) with a definite diagnosis of IBD. Demographic and clinical data and also alanine transaminase levels were collected for both cohorts. The Catanzaro cohort underwent liver evaluation by sonography and liver stiffness and controlled attenuation parameter measurements by transient elastography.

RESULTS

Here, we show for the first time that carriers of the PNPLA3 148M allele with IBD have a greater risk of hepatic steatosis (odds ratio, 2.9, and confidence interval, 1.1-7.8), higher controlled attenuation parameter values (P = 0.029), and increased circulating alanine transaminase (P = 0.035) in the Catanzaro cohort. We further confirm the higher alanine transaminase levels in the Milan cohort (P < 0.001).

CONCLUSIONS

Our results show that PNPLA3 148M carriers with IBD have higher susceptibility to hepatic steatosis and liver damage.

Biliary tract external drainage protects against intestinal barrier injury in hemorrhagic shock rats

AIM: To investigate the effects of biliary tract external drainage (BTED) on intestinal barrier injury in rats with hemorrhagic shock (HS).

METHODS: BTED was performed via cannula insertion into the bile duct of rats. HS was induced by drawing blood from the femoral artery at a rate of 1 mL/min until a mean arterial pressure (MAP) of 40 ± 5 mmHg was achieved. That MAP was maintained for 60 min. A total of 99 Sprague-Dawley rats were randomized into a sham group, an HS group and an HS + BTED group. Nine rats in the sham group were sacrificed 0.5 h after surgery. Nine rats in each of the HS and HS + BTED groups were sacrificed 0.5 h, 1 h, 2 h, 4 h and 6 h after resuscitation. Plasma tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and lipopolysaccharide (LPS) levels were analyzed using enzyme-linked immunosorbent assay. Plasma D-lactate levels were analyzed using colorimetry. The expression levels of occludin and claudin-1 in the ileum were analyzed using Western blot and immunohistochemistry. Histology of the ileum was evaluated by hematoxylin and eosin staining.

RESULTS: Plasma TNF-α levels in the HS + BTED group decreased significantly compared with the HS group at 1 h and 6 h after resuscitation (P < 0.05). Plasma IL-6 levels in the HS + BTED group decreased significantly compared with the HS group at 0.5 h, 1 h and 2 h after resuscitation (P < 0.05). Plasma D-lactate and LPS levels in the HS + BTED group decreased significantly compared with the HS group at 6 h after resuscitation (P < 0.05). The expression levels of occludin in the HS + BTED group increased significantly compared with the HS group at 4 h and 6 h after resuscitation (P < 0.05). The expression levels of claudin-1 in the HS + BTED group increased significantly compared with the HS group at 6 h after resuscitation (P < 0.05). Phenomena of putrescence and desquamation of epithelial cells in the ileal mucosa were attenuated in the HS + BTED group. Ileal histopathologic scores in the HS + BTED group decreased significantly compared with the HS group at 2 h, 4 h and 6 h after resuscitation (P < 0.05).

CONCLUSION: BTED protects against intestinal barrier injury in HS rats.

Abnormal Liver Biochemistry Is Common in Pediatric Inflammatory Bowel Disease: Prevalence and Associations

BACKGROUND

Liver enzymes (LEs) abnormalities associated with pediatric inflammatory bowel diseases (IBD) are understudied. We undertook to describe the development and associations of abnormal LEs in pediatric IBD.

METHODS

We ascertained a cohort of 300 children with IBD and collected retrospective data. A Kaplan-Meier analysis determined the time to development of different thresholds of abnormal LEs. Associations between clinical variables and the development of abnormal LEs were determined.

RESULTS

The probability of developing the first episode of abnormal LEs above the upper limit of normal (ULN) within 150 months was 58.1% (16.3% by 1 mo post-IBD diagnosis). There was a 6% prevalence of primary sclerosing cholangitis (PSC) or autoimmune sclerosing cholangitis (ASC) in this cohort. Of those diagnosed with PSC/ASC, 93% had persistent LE elevations at a threshold of >2× ULN, while those without PSC/ASC had a 4% probability of this abnormality. Elevated gamma glutamyltranspeptidase levels of 252 U/L had a 99% sensitivity and 71% specificity for PSC/ASC in IBD. After exclusion of patients with PSC/ASC, corticosteroids, antibiotics, and exclusive enteral nutrition demonstrated strongly positive associations with the first development of abnormal LEs >ULN (hazard ratio 2.1 [95% confidence interval, 1.3-3.3], hazard ratio 5.6 [95% confidence interval, 3.6-8.9], hazard ratio 4.2 [95% confidence interval, 1.6-11.3], respectively).

CONCLUSIONS

Abnormal LEs are common in pediatric IBD and occur early. PSC/ASC is associated with persistently high LEs and gamma glutamyltranspeptidase levels >252 U/L. Children with IBD are at risk of elevated LEs if they require medications other than 5-ASA to induce IBD remission.

Gut microbiota and host metabolism in liver cirrhosis

The gut microbiota has the capacity to produce a diverse range of compounds that play a major role in regulating the activity of distal organs and the liver is strategically positioned downstream of the gut. Gut microbiota linked compounds such as short chain fatty acids, bile acids, choline metabolites, indole derivatives, vitamins, polyamines, lipids, neurotransmitters and neuroactive compounds, and hypothalamic-pituitary-adrenal axis hormones have many biological functions. This review focuses on the gut microbiota and host metabolism in liver cirrhosis. Dysbiosis in liver cirrhosis causes serious complications, such as bacteremia and hepatic encephalopathy, accompanied by small intestinal bacterial overgrowth and increased intestinal permeability. Gut dysbiosis in cirrhosis and intervention with probiotics and synbiotics in a clinical setting is reviewed and evaluated. Recent studies have revealed the relationship between gut microbiota and host metabolism in chronic metabolic liver disease, especially, non-alcoholic fatty liver disease, alcoholic liver disease, and with the gut microbiota metabolic interactions in dysbiosis related metabolic diseases such as diabetes and obesity. Recently, our understanding of the relationship between the gut and liver and how this regulates systemic metabolic changes in liver cirrhosis has increased. The serum lipid levels of phospholipids, free fatty acids, polyunsaturated fatty acids, especially, eicosapentaenoic acid, arachidonic acid, and docosahexaenoic acid have significant correlations with specific fecal flora in liver cirrhosis. Many clinical and experimental reports support the relationship between fatty acid metabolism and gut-microbiota. Various blood metabolome such as cytokines, amino acids, and vitamins are correlated with gut microbiota in probiotics-treated liver cirrhosis patients. The future evaluation of the gut-microbiota-liver metabolic network and the intervention of these relationships using probiotics, synbiotics, and prebiotics, with sufficient nutrition could aid the development of treatments and prevention for liver cirrhosis patients.

The Art and Science of Diagnosing and Managing Drug-induced Liver Injury in 2015 and Beyond

Drug-induced liver injury (DILI) remains a leading reason why new compounds are dropped from further study or are the subject of product warnings and regulatory actions. Hy's Law of drug-induced hepatocellular jaundice causing a case-fatality rate or need for transplant of 10% or higher has been validated in several large national registries, including the ongoing, prospective U.S. Drug-Induced Liver Injury Network. It serves as the basis for stopping rules in clinical trials and in clinical practice. Because DILI can mimic all known causes of acute and chronic liver disease, establishing causality can be difficult. Histopathologic findings are often nonspecific and rarely, if ever, considered pathognomonic. A daily drug dose >50-100 mg is more likely to be hepatotoxic than does <10 mg, especially if the compound is highly lipophilic or undergoes extensive hepatic metabolism. The quest for a predictive biomarker to replace alanine aminotransferase is ongoing. Markers of necrosis and apoptosis such as microRNA-122 and keratin 18 may prove useful in identifying patients at risk for severe injury when they initially present with a suspected acetaminophen overdose. Although a number of drugs causing idiosyncratic DILI have HLA associations that may allow for pre-prescription testing to prevent hepatotoxicity, the cost and relatively low frequency of injury among affected patients limit the current usefulness of such genome-wide association studies. Alanine aminotransferase monitoring is often recommended but has rarely been shown to be an effective method to prevent serious DILI. Guidelines on the diagnosis and management of DILI have recently been published, although specific therapies remain limited. The LiverTox Web site has been introduced as an interactive online virtual textbook that makes the latest information on more than 650 agents available to clinicians, regulators, and drug developers alike.

Gut microbiota and liver diseases

Several studies revealed that gut microbiota are associated with various human diseases, e.g., metabolic diseases, allergies, gastroenterological diseases, and liver diseases. The liver can be greatly affected by changes in gut microbiota due to the entry of gut bacteria or their metabolites into the liver through the portal vein, and the liver-gut axis is important to understand the pathophysiology of several liver diseases, especially non-alcoholic fatty liver disease and hepatic encephalopathy. Moreover, gut microbiota play a significant role in the development of alcoholic liver disease and hepatocarcinogenesis. Based on these previous findings, trials using probiotics have been performed for the prevention or treatment of liver diseases. In this review, we summarize the current understanding of the changes in gut microbiota associated with various liver diseases, and we describe the therapeutic trials of probiotics for those diseases.

Non-alcoholic fatty liver disease in obese adults: clinical aspects and current management strategies

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disorder whose prevalence is strongly linked to the current epidemic of obesity in many western countries. The prevalence of NAFLD is two to four times higher in populations with pre-existing metabolic comorbidities than in the general population. The diagnosis of primary NAFLD involves establishing the presence of hepatic steatosis or steatohepatitis by imaging or histology, along with establishing the non-alcoholic nature of the disease process and excluding competing aetiologies for hepatic steatosis. Among the indirect serum biomarkers, the NAFLD fibrosis score can help to identify patients with NAFLD and with higher likelihood of having fibrosis or cirrhosis. A liver biopsy should be considered in NAFLD patients at increased risk for steatohepatitis/advanced fibrosis and in cases where a liver biopsy is necessary to exclude co-existing chronic liver diseases and other aetiologies for hepatic steatosis. The treatment and management recommendations for obesity-associated NAFLD are aimed towards weight reduction. The currently available interventions employed to promote weight loss and improve the metabolic responses in NAFLD include lifestyle modification, pharmacotherapy and bariatric surgery.

Minireview: Gut microbiota: the neglected endocrine organ

The concept that the gut microbiota serves as a virtual endocrine organ arises from a number of important observations. Evidence for a direct role arises from its metabolic capacity to produce and regulate multiple compounds that reach the circulation and act to influence the function of distal organs and systems. For example, metabolism of carbohydrates results in the production of short-chain fatty acids, such as butyrate and propionate, which provide an important source of nutrients as well as regulatory control of the host digestive system. This influence over host metabolism is also seen in the ability of the prebiotic inulin to influence production of relevant hormones such as glucagon-like peptide-1, peptide YY, ghrelin, and leptin. Moreover, the probiotic Lactobacillus rhamnosus PL60, which produces conjugated linoleic acid, has been shown to reduce body-weight gain and white adipose tissue without effects on food intake. Manipulating the microbial composition of the gastrointestinal tract modulates plasma concentrations of tryptophan, an essential amino acid and precursor to serotonin, a key neurotransmitter within both the enteric and central nervous systems. Indirectly and through as yet unknown mechanisms, the gut microbiota exerts control over the hypothalamic-pituitary-adrenal axis. This is clear from studies on animals raised in a germ-free environment, who show exaggerated responses to psychological stress, which normalizes after monocolonization by certain bacterial species including Bifidobacterium infantis. It is tempting to speculate that therapeutic targeting of the gut microbiota may be useful in treating stress-related disorders and metabolic diseases.

Meta-omic platforms to assist in the understanding of NAFLD gut microbiota alterations: tools and applications

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease worldwide as a result of the increasing prevalence of obesity, starting from early life stages. It is characterized by a spectrum of liver diseases ranging from simple fatty liver (NAFL) to steatohepatitis (NASH), with a possible progression to fibrosis, thus increasing liver-related morbidity and mortality. NAFLD development is driven by the co-action of several risk factors, including obesity and metabolic syndrome, which may be both genetically induced and diet-related. Recently, particular attention has been paid to the gut-liver axis, which may play a physio-pathological role in the onset and progression of the disease. The gut microbiota is intended to act as a bioreactor that can guarantee autonomous metabolic and immunological functions and that can drive functional strategies within the environment of the body in response to external stimuli. The complexity of the gut microbiota suggests that it behaves as an organ. Therefore, the concept of the gut-liver axis must be complemented with the gut-microbiota-liver network due to the high intricacy of the microbiota components and metabolic activities; these activities form the active diet-driven power plant of the host. Such complexity can only be revealed using systems biology, which can integrate clinical phenomics and gut microbiota data.