Characterization of fecal microbial communities in patients with liver cirrhosis

Targeting the gut-liver axis in cirrhosis: antibiotics and non-selective β-blockers

The gut-liver axis in cirrhosis and portal hypertension is gaining increasing attention as a key pathophysiological mechanism responsible for progression of liver failure and development of complications such as spontaneous infections and hepatocellular carcinoma. Antibiotics and non-selective β-blockers (NSBB) intercept this axis and each drug has proven efficacy in clinical trials. A synergistic effect is a hitherto unproven possibility. There is an increasing body of evidence supporting improved outcome with expanded use of NSBB and antibiotic therapy beyond current indications. This review addresses the issue of pharmacological treatment of cirrhosis and portal hypertension with antibiotics and NSBB. We discuss their mechanism of action and suggest that combining the two treatment modalities could potentially reduce the risk of complications.

Gut microbiota and hepatic encephalopathy

There is a strong relationship between liver and gut; while the portal venous system receives blood from the gut, and its contents may affect liver functions, liver in turn, affects intestinal functions through bile secretion. There is robust evidence that the pathogenesis of hepatic encephalopathy (HE) is linked to alterations in gut microbiota and their by-products such as ammonia, indoles, oxindoles, endotoxins, etc. In the setting of intestinal barrier and immune dysfunction, these by-products are involved in the pathogenesis of complications of liver cirrhosis including HE and systemic inflammation plays an important role. Prebiotics, probiotics and synbiotics may exhibit efficacy in the treatment of HE by modulating the gut flora. They improve derangement in flora by decreasing the counts of pathogenic bacteria and thus improving the endotoxemia, HE and the liver disease. Current evidence suggest that the trials evaluating the role of probiotics in the treatment of HE are of not high quality and all trials had high risk of bias and high risk of random errors. Therefore, the use of probiotics for patients with HE cannot be currently recommended. Further RCTs are required. This review summarizes the main literature findings about the relationships between gut flora and HE, both in terms of the pathogenesis and the treatment of HE.

Ethanol metabolism and its effects on the intestinal epithelial barrier

Ethanol is widely consumed and is associated with an increasing global health burden. Several reviews have addressed the effects of ethanol and its oxidative metabolite, acetaldehyde, on the gastrointestinal (GI) tract, focusing on carcinogenic effects or alcoholic liver disease. However, both the oxidative and the nonoxidative metabolites of ethanol can affect the epithelial barrier of the small and large intestines, thereby contributing to GI and liver diseases. This review outlines the possible mechanisms of ethanol metabolism as well as the effects of ethanol and its metabolites on the intestinal barrier. Limited studies in humans and supporting in vitro data have indicated that ethanol as well as mainly acetaldehyde can increase small intestinal permeability. Limited evidence also points to increased colon permeability following exposure to ethanol or acetaldehyde. In vitro studies have provided several mechanisms for disruption of the epithelial barrier, including activation of different cell-signaling pathways, oxidative stress, and remodeling of the cytoskeleton. Modulation via intestinal microbiota, however, should also be considered. In conclusion, ethanol and its metabolites may act additively or even synergistically in vivo. Therefore, in vivo studies investigating the effects of ethanol and its byproducts on permeability of the small and large intestines are warranted.

Modulation of the fecal bile acid profile by gut microbiota in cirrhosis

BACKGROUND & AIMS

The 7α-dehydroxylation of primary bile acids (BAs), chenodeoxycholic (CDCA) and cholic acid (CA) into the secondary BAs, lithocholic (LCA) and deoxycholic acid (DCA), is a key function of the gut microbiota. We aimed at studying the linkage between fecal BAs and gut microbiota in cirrhosis since this could help understand cirrhosis progression.

METHODS

Fecal microbiota were analyzed by culture-independent multitagged-pyrosequencing, fecal BAs using HPLC and serum BAs using LC-MS in controls, early (Child A) and advanced cirrhotics (Child B/C). A subgroup of early cirrhotics underwent BA and microbiota analysis before/after eight weeks of rifaximin.

RESULTS

Cross-sectional: 47 cirrhotics (24 advanced) and 14 controls were included. In feces, advanced cirrhotics had the lowest total, secondary, secondary/primary BA ratios, and the highest primary BAs compared to early cirrhotics and controls. Secondary fecal BAs were detectable in all controls but in a significantly lower proportion of cirrhotics (p<0.002). Serum primary BAs were higher in advanced cirrhotics compared to the rest. Cirrhotics, compared to controls, had a higher Enterobacteriaceae (potentially pathogenic) but lower Lachonospiraceae, Ruminococcaceae and Blautia (7α-dehydroxylating bacteria) abundance. CDCA was positively correlated with Enterobacteriaceae (r=0.57, p<0.008) while Ruminococcaceae were positively correlated with DCA (r=0.4, p<0.05). A positive correlation between Ruminococcaceae and DCA/CA (r=0.82, p<0.012) and Blautia with LCA/CDCA (r=0.61, p<0.03) was also seen. Prospective study: post-rifaximin, six early cirrhotics had reduction in Veillonellaceae and in secondary/primary BA ratios.

CONCLUSIONS

Cirrhosis, especially advanced disease, is associated with a decreased conversion of primary to secondary fecal BAs, which is linked to abundance of key gut microbiome taxa.

Gut microbial diversity is reduced and is associated with colonic inflammation in a piglet model of short bowel syndrome

BACKGROUND AND OBJECTIVES

Following small bowel resection (SBR), the luminal environment is altered, which contributes to clinical manifestations of short bowel syndrome (SBS) including malabsorption, mucosal inflammation and bacterial overgrowth. However, the impact of SBR on the colon has not been well-defined. The aims of this study were to characterize the colonic microbiota following SBR and to assess the impact of SBR on mucosal inflammation in the colon.

RESULTS

Analysis of the colonic microbiota demonstrated that there was a significant level of dysbiosis both two and six weeks post-SBR, particularly in the phylum Firmicutes, coupled with a decrease in overall bacterial diversity in the colon. This decrease in diversity was associated with an increase in colonic inflammation six weeks post-surgery.

METHODS

Female (4-week old) piglets (5-6/group) received a 75% SBR, a transection (sham) or no surgery. Compositional analysis of the colonic microbiota was performed by high-throughput sequencing, two- and six-weeks post-surgery. The gene expression of the pro-inflammatory cytokines interleukin (IL)-1β, IL-6, IL-8, IL-18 and tumor necrosis factor (TNF)-α in the colonic mucosa was assessed by qRT-PCR and the number of macrophages and percentage inducible nitric oxide synthase (iNOS) staining in the colonic epithelium were quantified by immunohistochemistry.

CONCLUSIONS

SBR significantly decreased the diversity of the colonic microbiota and this was associated with an increase in colonic mucosal inflammation. This study supports the hypothesis that SBR has a significant impact on the colon and that this may play an important role in defining clinical outcome.

Decreased dietary fiber intake and structural alteration of gut microbiota in patients with advanced colorectal adenoma

BACKGROUND

Accumulating evidence indicates that diet is one of the most important environmental factors involved in the progression from advanced colorectal adenoma (A-CRA) to colorectal cancer.

OBJECTIVE

We evaluated the possible effects of dietary fiber on the fecal microbiota of patients with A-CRA.

DESIGN

Patients with a diagnosis of A-CRA by pathological examination were enrolled in the A-CRA group. Patients with no obvious abnormalities or histopathological changes were enrolled in the healthy control (HC) group. Dietary fiber intake was assessed in all patients. Short-chain fatty acids (SCFAs) in feces were detected by gas chromatography. The fecal microbiota community was analyzed by 454 pyrosequencing based on 16S ribosomal RNA.

RESULTS

Lower dietary fiber patterns and consistently lower SCFA production were observed in the A-CRA group (n = 344). Principal component analysis showed distinct differences in the fecal microbiota communities of the 2 groups. Clostridium, Roseburia, and Eubacterium spp. were significantly less prevalent in the A-CRA group (n = 47) than in the HC group (n = 47), whereas Enterococcus and Streptococcus spp. were more prevalent in the A-CRA group (n = 47) (all P < 0.05). Butyrate and butyrate-producing bacteria were more prevalent in a subgroup of HC subjects with a high fiber intake than in those in both the low-fiber HC subgroup and the high-fiber A-CRA subgroup (all P < 0.05).

CONCLUSION

A high-fiber dietary pattern and subsequent consistent production of SCFAs and healthy gut microbiota are associated with a reduced risk of A-CRA. This trial was registered at www.chictr.org as ChiCTR-TRC-00000123.

Linking intestinal homeostasis and liver disease

PURPOSE OF REVIEW

Interactions of the gut microbiome with the host are important in health and disease. Microbial translocation releases bacterial products that play a key role in progression of chronic liver disease by promoting hepatic injury and inflammation. Although this has long been recognized, we are just beginning to understand the circumstances under which the gut becomes leaky and to discover bacterial metabolites that promote liver disease. In this review, we will summarize recent findings from the last 2 years.

RECENT FINDINGS

Chronic liver disease is associated with an altered microbiome with both qualitative (dysbiosis) and quantitative (overgrowth) differences. This can be viewed as a loss of the symbiotic relationship between the microflora and the host. An imbalanced intestinal homeostasis results in a breach of the gut barrier and subsequent microbial translocation. However, the contribution of the intestinal microflora is beyond simple microbial translocation as a pathogenic factor. Bacterial metabolites resulting from an imbalanced homeostasis and dysbiosis play also a crucial role in liver disease.

SUMMARY

A combination between an initiating liver insult and a disturbance of the gut-host symbiosis synergize in progression of liver disease.

Modulation of the metabiome by rifaximin in patients with cirrhosis and minimal hepatic encephalopathy

Hepatic encephalopathy (HE) represents a dysfunctional gut-liver-brain axis in cirrhosis which can negatively impact outcomes. This altered gut-brain relationship has been treated using gut-selective antibiotics such as rifaximin, that improve cognitive function in HE, especially its subclinical form, minimal HE (MHE). However, the precise mechanism of the action of rifaximin in MHE is unclear. We hypothesized that modulation of gut microbiota and their end-products by rifaximin would affect the gut-brain axis and improve cognitive performance in cirrhosis. Aim To perform a systems biology analysis of the microbiome, metabolome and cognitive change after rifaximin in MHE.

METHODS

Twenty cirrhotics with MHE underwent cognitive testing, endotoxin analysis, urine/serum metabolomics (GC and LC-MS) and fecal microbiome assessment (multi-tagged pyrosequencing) at baseline and 8 weeks post-rifaximin 550 mg BID. Changes in cognition, endotoxin, serum/urine metabolites (and microbiome were analyzed using recommended systems biology techniques. Specifically, correlation networks between microbiota and metabolome were analyzed before and after rifaximin.

RESULTS

There was a significant improvement in cognition(six of seven tests improved, p<0.01) and endotoxemia (0.55 to 0.48 Eu/ml, p = 0.02) after rifaximin. There was a significant increase in serum saturated (myristic, caprylic, palmitic, palmitoleic, oleic and eicosanoic) and unsaturated (linoleic, linolenic, gamma-linolenic and arachnidonic) fatty acids post-rifaximin. No significant microbial change apart from a modest decrease in Veillonellaceae and increase in Eubacteriaceae was observed. Rifaximin resulted in a significant reduction in network connectivity and clustering on the correlation networks. The networks centered on Enterobacteriaceae, Porphyromonadaceae and Bacteroidaceae indicated a shift from pathogenic to beneficial metabolite linkages and better cognition while those centered on autochthonous taxa remained similar.

CONCLUSIONS

Rifaximin is associated with improved cognitive function and endotoxemia in MHE, which is accompanied by alteration of gut bacterial linkages with metabolites without significant change in microbial abundance.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01069133.

The dynamic biliary epithelia: molecules, pathways, and disease

Cholangiocytes, the cells lining bile ducts, are a heterogenous, highly dynamic population of epithelial cells. While these cells comprise a small fraction of the total cellular component of the liver, they perform the essential role of bile modification and transport of biliary and blood constituents. From a pathophysiological standpoint, cholangiocytes are the target of a diverse group of biliary disorders, collectively referred to as the cholangiopathies. To date, the cause of most cholangiopathies remains obscure. It is known, however, that cholangiocytes exist in an environment rich in potential mediators of cellular injury, express receptors that recognize potential injurious insults, and participate in portal tract repair processes following hepatic injury. As such, cholangiocytes may not be only a passive target, but are likely directly and actively involved in the pathogenesis of cholangiopathies. Here, we briefly summarize the characteristics of the reactive cholangiocyte and cholangiocyte responses to potentially injurious endogenous and exogenous molecules, and in addition, present emerging concepts in our understanding of the etiopathogenesis of several cholangiopathies.

The intestinal microbiota in chronic liver disease

Recent evidence indicates that the intestinal microflora plays a critical role in physiological and pathological processes; in particular, it is now considered a key determinant of immune pathologies and metabolic syndrome. Receiving the majority of its blood supply from the portal vein, the liver represents the first line of defense against food antigens, toxins, microbial-derived products, and microorganisms. Moreover, the liver is critically positioned to integrate metabolic outcomes with nutrient intake. To accomplish this function, the liver is equipped with a broad array of immune networks. It is now evident that, during pathological processes associated with obesity, alcohol-intake, or autoimmunity, the interaction between these immune cell populations and the intestinal microbiota promotes chronic liver disease progression and therefore they represent a novel therapeutic target. Herein, we highlight recent studies that have shed new light on the relationship between the microbiome, the innate immune system, and chronic liver disease progression.

The role of gut-liver axis in the pathogenesis of liver cirrhosis and portal hypertension

Because of the anatomical position and its unique vascular system, the liver is susceptible to the exposure to the microbial products from the gut. Although large amount of microbes colonize in the gut, translocation of the microbes or microbial products into the liver and systemic circulation is prevented by gut epithelial barrier function and cleansing and detoxifying functions of the liver in healthy subjects. However, when the intestinal barrier function is disrupted, large amount of bacterial products can enter into the liver and systemic circulation and induce inflammation through their receptors. Nowadays, there have been various reports suggesting the role of gut flora and bacterial translocation in the pathogenesis of chronic liver disease and portal hypertension. This review summarizes the current knowledge about bacterial translocation and its contribution to the pathogenesis of chronic liver diseases and portal hypertension.

Second infections independently increase mortality in hospitalized patients with cirrhosis: the North American consortium for the study of end-stage liver disease (NACSELD) experience

Bacterial infections are an important cause of mortality in cirrhosis, but there is a paucity of multicenter studies. The aim was to define factors predisposing to infection-related mortality in hospitalized patients with cirrhosis. A prospective, cohort study of patients with cirrhosis with infections was performed at eight North American tertiary-care hepatology centers. Data were collected on admission vitals, disease severity (model for endstage liver disease [MELD] and sequential organ failure [SOFA] scores), first infection site, type (community-acquired, healthcare-associated [HCA] or nosocomial), and second infection occurrence during hospitalization. The outcome was mortality within 30 days. A multivariate logistic regression model predicting mortality was created. 207 patients (55 years, 60% men, MELD 20) were included. Most first infections were HCA (71%), then nosocomial (15%) and community-acquired (14%). Urinary tract infections (52%), spontaneous bacterial peritonitis (SBP, 23%) and spontaneous bacteremia (21%) formed the majority of the first infections. Second infections were seen in 50 (24%) patients and were largely preventable: respiratory, including aspiration (28%), urinary, including catheter-related (26%), fungal (14%), and Clostridium difficile (12%) infections. Forty-nine patients (23.6%) who died within 30 days had higher admission MELD (25 versus 18, P < 0.0001), lower serum albumin (2.4 g/dL versus 2.8 g/dL, P = 0.002), and second infections (49% versus 16%, P < 0.0001) but equivalent SOFA scores (9.2 versus 9.9, P = 0.86). The case fatality rate was highest for C. difficile (40%), respiratory (37.5%), and spontaneous bacteremia (37%), and lowest for SBP (17%) and urinary infections (15%). The model for mortality included admission MELD (odds ratio [OR]: 1.12), heart rate (OR: 1.03) albumin (OR: 0.5), and second infection (OR: 4.42) as significant variables.

CONCLUSION

Potentially preventable second infections are predictors of mortality independent of liver disease severity in this multicenter cirrhosis cohort.

The intestinal microbiome and the leaky gut as therapeutic targets in alcoholic liver disease

Alcoholic liver disease (ALD) encompasses hepatic steatosis, which may progress to alcoholic hepatitis, fibrosis, and cirrhosis. It remains a leading cause of morbidity and mortality in the US and worldwide. The severity of liver disease correlates with plasma levels of bacterial products in patients, and experimental ALD depends on the level of gut derived bacterial products in rodents. Since intestinal decontamination and deficiency of bacterial product receptors or their downstream signaling molecules protect from alcohol-induced liver disease, bacterial translocation (BT), qualitative, and quantitative changes of the enteric microbiome are considered as being of fundamental importance in the pathogenesis of ALD. Recent enhancements in diagnostic technologies provide a better insight into these shifts. This review highlights vital events in ALD such as BT, the importance of Toll-like receptor (TLR) signaling, intestinal bacterial overgrowth (IBO), and changes in the intestinal microbiome. Furthermore, a treatment trial section of patients reviews possible future options of therapy for ALD modifying the enteric microbiome.

Changes in intestinal microflora in patients with hepatic cirrhosis

AIM: To compare the differences in the numbers of Bifidobacterium, Bacteroides, Eubacterium rectale-Clostridium, Escherichia coli, Enterococcus, Clostridium difficile in stool samples between patients with hepatic cirrhosis and controls to understand the changes in intestinal flora in patients with hepatic cirrhosis.

METHODS: Stool samples collected from 29 patients with hepatic cirrhosis who were treated at the First People's Hospital of Zunyi during the period between March to December 2010 and 13 healthy volunteers were used in this study. The samples were fixed, smeared on slides, and analyzed by fluorescent in situ hybridization (FISH) and laser scanning confocal microscopy (LSCM). The t-test and rank correlation test were used for statistical analysis.

RESULTS: The numbers of Bifidobacterium, Bacteroides, Eubacterium rectale-Clostridium, Escherichia coli, Enterococcus, and Clostridium difficile were significantly lower in patients with hepatic cirrhosis than in controls (Z = -4.006, -4.34, -4.399, -4.174, -3.558, -3.95; all P < 0.01). The proportions of all 6 kinds of bacteria were changed. The numbers of obligate anaerobes such as Bifidobacteria and Bacteroides were reduced, while those of E. coli, Eubacterium rectale-Clostridium, Enterococcus, and ClostriDium difficile were increased (all P < 0.05). The numbers and portions of bacteria had no significant correlation with etiology and severity of hepatic cirrhosis (Child-Pugh classification).

CONCLUSION: The numbers and proportions of six kinds of bacteria changed in patients with hepatic cirrhosis. Changes in intestinal microflora have no significant correlation with etiology and Child-Pugh classification.

Colonic mucosal microbiome differs from stool microbiome in cirrhosis and hepatic encephalopathy and is linked to cognition and inflammation

Although hepatic encephalopathy (HE) is linked to the gut microbiota, stool microbiome analysis has not found differences between HE and no-HE patients. This study aimed to compare sigmoid mucosal microbiome of cirrhotic patients to controls, between HE vs. no-HE patients, and to study their linkage with cognition and inflammation. Sixty cirrhotic patients (36 HE and 24 no-HE) underwent cognitive testing, stool collection, cytokine (Th1, Th2, Th17, and innate immunity), and endotoxin analysis. Thirty-six patients (19 HE and 17 no-HE) and 17 age-matched controls underwent sigmoid biopsies. Multitag pyrosequencing (including autochthonous genera, i.e., Blautia, Roseburia, Fecalibacterium, Dorea) was performed on stool and mucosa. Stool and mucosal microbiome differences within/between groups and correlation network analyses were performed. Controls had significantly higher autochthonous and lower pathogenic genera compared with cirrhotic patients, especially HE patients. HE patients had worse MELD (model for end-stage liver disease) score and cognition and higher IL-6 and endotoxin than no-HE. Mucosal microbiota was different from stool within both HE/no-HE groups. Between HE/no-HE patients, there was no difference in stool microbiota but mucosal microbiome was different with lower Roseburia and higher Enterococcus, Veillonella, Megasphaera, and Burkholderia abundance in HE. On network analysis, autochthonous genera (Blautia, Fecalibacterium, Roseburia, and Dorea) were associated with good cognition and decreased inflammation in both HE/no-HE, whereas genera overrepresented in HE (Enterococcus, Megasphaera, and Burkholderia) were linked to poor cognition and inflammation. Sigmoid mucosal microbiome differs significantly from stool microbiome in cirrhosis. Cirrhotic, especially HE, patients' mucosal microbiota is significantly different from controls with a lack of potentially beneficial autochthonous and overgrowth of potentially pathogenic genera, which are associated with poor cognition and inflammation.

Human intestinal lumen and mucosa-associated microbiota in patients with colorectal cancer

Recent reports have suggested the involvement of gut microbiota in the progression of colorectal cancer (CRC). We utilized pyrosequencing based analysis of 16S rRNA genes to determine the overall structure of microbiota in patients with colorectal cancer and healthy controls; we investigated microbiota of the intestinal lumen, the cancerous tissue and matched noncancerous normal tissue. Moreover, we investigated the mucosa-adherent microbial composition using rectal swab samples because the structure of the tissue-adherent bacterial community is potentially altered following bowel cleansing. Our findings indicated that the microbial structure of the intestinal lumen and cancerous tissue differed significantly. Phylotypes that enhance energy harvest from diets or perform metabolic exchange with the host were more abundant in the lumen. There were more abundant Firmicutes and less abundant Bacteroidetes and Proteobacteria in lumen. The overall microbial structures of cancerous tissue and noncancerous tissue were similar; howerer the tumor microbiota exhibited lower diversity. The structures of the intestinal lumen microbiota and mucosa-adherent microbiota were different in CRC patients compared to matched microbiota in healthy individuals. Lactobacillales was enriched in cancerous tissue, whereas Faecalibacterium was reduced. In the mucosa-adherent microbiota, Bifidobacterium, Faecalibacterium, and Blautia were reduced in CRC patients, whereas Fusobacterium, Porphyromonas, Peptostreptococcus, and Mogibacterium were enriched. In the lumen, predominant phylotypes related to metabolic disorders or metabolic exchange with the host, Erysipelotrichaceae, Prevotellaceae, and Coriobacteriaceae were increased in cancer patients. Coupled with previous reports, these results suggest that the intestinal microbiota is associated with CRC risk and that intestinal lumen microflora potentially influence CRC risk via cometabolism or metabolic exchange with the host. However, mucosa-associated microbiota potentially affects CRC risk primarily through direct interaction with the host.

Higher-level production of volatile fatty acids in vitro by chicken gut microbiotas than by human gut microbiotas as determined by functional analyses

The aim of this study was to determine the relationship between the composition and function of gut microbiota. Here, we compared the bacterial compositions and fermentation metabolites of human and chicken gut microbiotas. Results generated by quantitative PCR (qPCR) and 454 pyrosequencing of the 16S rRNA gene V3 region showed the compositions of human and chicken microbiotas to be markedly different, with chicken cecal microbiotas displaying more diversity than human fecal microbiotas. The nutrient requirements of each microbiota growing under batch and chemostat conditions were analyzed. The results showed that chicken cecal microbiotas required simple sugars and peptides to maintain balanced growth in vitro but that human fecal microbiotas preferred polysaccharides and proteins. Chicken microbiotas also produced higher concentrations of volatile fatty acids than did human microbiotas. Our data suggest that the availability of different fermentable substrates in the chicken cecum, which exist due to the unique anatomical structure of the cecum, may provide an environment favorable to the nourishment of microbiotas suited to the production of the higher-energy metabolites required by the bird. Therefore, gut structure, nutrition, immunity, and life-style all contribute to the selection of an exclusive bacterial community that produces types of metabolites beneficial to the host.

A longitudinal systems biology analysis of lactulose withdrawal in hepatic encephalopathy

The pathogenesis of hepatic encephalopathy(HE) is unclear. However gut flora changes, inflammation and neuro-glial injury have been implicated. The aim was to evaluate factors that were associated with HE recurrence after lactulose withdrawal by analyzing the clinical phenotype, stool microbiome and systemic metabolome longitudinally. HE patients on a standard diet who were adherent on lactulose underwent characterization of their phenotype [cognition, inflammatory cytokines, in-vivo brain MR spectroscopy(MRS)], gut microbiome (stool Multitag Pyrosequencing) and metabolome (urine/serum ex-vivo MRS) analysis while on lactulose and on days 2, 14 and 30 post-withdrawal. Patients whose HE recurred post-withdrawal were compared to those without recurrence. We included seven men (53 ± 8 years) who were adherent on lactulose after a precipitated HE episode were included. HE recurred in three men 32 ± 6 days post-withdrawal. In-vivo brain MRS showed increased glutamine+glutamate (Glx) and decreased myoinositol with a reduction in stool Faecalibacterium spp., post-withdrawal. HE recurrence was predicted by poor baseline inhibitory control and block design performance and was associated with a shift of choline metabolism from tri-methylamine oxide formation towards the development of di-methylglycine, glycine and creatinine. This was accompanied by a mixed effect on the immune response (suppressed IL-10 and Th1/Th2/Th17 response). The correlation network showed Prevotella to be linked to improved cognition and decreased inflammation in patients without HE recurrence. We conclude that lactulose withdrawal results in worsening cognition, mixed inflammatory response effect, lowered stool Faecalibacterium and increase in MR-measurable brain Glx. HE recurrence post-lactulose withdrawal can be predicted by baseline cognitive performance and is accompanied by disrupted choline metabolism.

Toll-like receptors in liver fibrosis: cellular crosstalk and mechanisms

Toll-like receptors (TLRs) are pattern recognition receptors that distinguish conserved microbial products, also known as pathogen-associated molecular patterns (PAMPs), from host molecules. Liver is the first filter organ between the gastrointestinal tracts and the rest of the body through portal circulation. Thus, the liver is a major organ that must deal with PAMPs and microorganisms translocated from the intestine and to respond to the damage associated molecular patterns (DAMPs) released from injured organs. These PAMPs and DAMPs preferentially activate TLR signaling on various cell types in the liver inducing the production of inflammatory and fibrogenic cytokines that initiate and prolong liver inflammation, thereby leading to fibrosis. We summarize recent findings on the role of TLRs, ligands, and intracellular signaling in the pathophysiology of liver fibrosis due to different etiology, as well as to highlight the potential role of TLR signaling in liver fibrosis associated with hepatitis C infection, non-alcoholic and alcoholic steatoheoatitis, primary biliary cirrhosis, and cystic fibrosis.

Assessment of the fecal lactobacilli population in patients with hepatitis B virus-related decompensated cirrhosis and hepatitis B cirrhosis treated with liver transplant

This study aims to provide an overview of the diversity of intestinal Lactobacillus among Chinese patients with hepatitis B virus (HBV)-related decompensated cirrhosis and who received liver transplant for hepatitis B cirrhosis. Fecal samples were collected from 38 healthy volunteers, 61 patients with HBV-related decompensated cirrhosis (group LC) and 74 patients who had liver transplant for hepatitis B cirrhosis (group LT). Quantitative polymerase chain reaction technology with species-specific primers was applied to investigate lactobacilli 16S rDNA in crude DNA, extracted from fecal samples. Software package Statistical Package for the Social Sciences and Palaeontological Statistics for Windows was used to analyze the data. Lactobacilli population of the two patient groups was different from the healthy control subjects, principal differences being marked decrease in the population of Lactobacillus rhamnosus (p < 0.001 for both patient groups) and reduction in the frequency of Lactobacillus fermentus (p < 0.001 for group LC and p < 0.01 for group LT). Our findings on the frequency of lactobacilli population suggested decreased diversity in groups LC and LT (compared with the healthy controls (p < 0.001 and p < 0.01, respectively)). Patients tended to have less complex fecal lactobacilli composition than the healthy controls, especially in the group LC.

Colonic microbiome is altered in alcoholism

Several studies indicate the importance of colonic microbiota in metabolic and inflammatory disorders and importance of diet on microbiota composition. The effects of alcohol, one of the prominent components of diet, on colonic bacterial composition is largely unknown. Mounting evidence suggests that gut-derived bacterial endotoxins are cofactors for alcohol-induced tissue injury and organ failure like alcoholic liver disease (ALD) that only occur in a subset of alcoholics. We hypothesized that chronic alcohol consumption results in alterations of the gut microbiome in a subgroup of alcoholics, and this may be responsible for the observed inflammatory state and endotoxemia in alcoholics. Thus we interrogated the mucosa-associated colonic microbiome in 48 alcoholics with and without ALD as well as 18 healthy subjects. Colonic biopsy samples from subjects were analyzed for microbiota composition using length heterogeneity PCR fingerprinting and multitag pyrosequencing. A subgroup of alcoholics have an altered colonic microbiome (dysbiosis). The alcoholics with dysbiosis had lower median abundances of Bacteroidetes and higher ones of Proteobacteria. The observed alterations appear to correlate with high levels of serum endotoxin in a subset of the samples. Network topology analysis indicated that alcohol use is correlated with decreased connectivity of the microbial network, and this alteration is seen even after an extended period of sobriety. We show that the colonic mucosa-associated bacterial microbiome is altered in a subset of alcoholics. The altered microbiota composition is persistent and correlates with endotoxemia in a subgroup of alcoholics.

Renal function at hospital admission and mortality due to acute kidney injury after myocardial infarction

BACKGROUND

The role of an impaired estimated glomerular filtration rate (eGFR) at hospital admission in the outcome of acute kidney injury (AKI) after acute myocardial infarction (AMI) has been underreported. The aim of this study was to assess the influence of an admission eGFR<60 mL/min/1.73 m(2) on the incidence and early and late mortality of AMI-associated AKI.

METHODS

A prospective study of 828 AMI patients was performed. AKI was defined as a serum creatinine increase of ≥ 50% from the time of admission (RIFLE criteria) in the first 7 days of hospitalization. Patients were divided into subgroups according to their eGFR upon hospital admission (MDRD formula, mL/min/1.73 m(2)) and the development of AKI: eGFR ≥ 60 without AKI, eGFR<60 without AKI, eGFR ≥ 60 with AKI and eGFR<60 with AKI.

RESULTS

Overall, 14.6% of the patients in this study developed AKI. The admission eGFR had no impact on the incidence of AKI. However, the admission eGFR was associated with the outcome of AMI-associated AKI. The adjusted hazard ratios (AHR, Cox multivariate analysis) for 30-day mortality were 2.00 (95% CI 1.11-3.61) for eGFR<60 without AKI, 4.76 (95% CI 2.45-9.26) for eGFR ≥ 60 with AKI and 6.27 (95% CI 3.20-12.29) for eGFR<60 with AKI. Only an admission eGFR of <60 with AKI was significantly associated with a 30-day to 1-year mortality hazard (AHR 3.05, 95% CI 1.50-6.19).

CONCLUSIONS

AKI development was associated with an increased early mortality hazard in AMI patients with either preserved or impaired admission eGFR. Only the association of impaired admission eGFR and AKI was associated with an increased hazard for late mortality among these patients.

The human microbiome: at the interface of health and disease

Interest in the role of the microbiome in human health has burgeoned over the past decade with the advent of new technologies for interrogating complex microbial communities. The large-scale dynamics of the microbiome can be described by many of the tools and observations used in the study of population ecology. Deciphering the metagenome and its aggregate genetic information can also be used to understand the functional properties of the microbial community. Both the microbiome and metagenome probably have important functions in health and disease; their exploration is a frontier in human genetics.

The human microbiome: at the interface of health and disease

Interest in the role of the microbiome in human health has burgeoned over the past decade with the advent of new technologies for interrogating complex microbial communities. The large-scale dynamics of the microbiome can be described by many of the tools and observations used in the study of population ecology. Deciphering the metagenome and its aggregate genetic information can also be used to understand the functional properties of the microbial community. Both the microbiome and metagenome probably have important functions in health and disease; their exploration is a frontier in human genetics.

Metabonomic profiles discriminate hepatocellular carcinoma from liver cirrhosis by ultraperformance liquid chromatography-mass spectrometry

Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide and usually develops in patients with liver cirrhosis (LC). Biomarkers that discriminate HCC from LC are important but are limited. In the present study, an ultraperformance liquid chromatography-mass spectrometry (UPLC-MS)-based metabonomics approach was used to characterize serum profiles from HCC (n = 82), LC (n = 48), and healthy subjects (n = 90), and the accuracy of UPLC-MS profiles and alpha-fetoprotein (AFP) levels were compared for their use in HCC diagnosis. By multivariate data and receiver operating characteristic curves analysis, metabolic profiles were capable of discriminating not only patients from the controls but also HCC from LC with 100% sensitivity and specificity. Thirteen potential biomarkers were identified and suggested that there were significant disturbances of key metabolic pathways, such as organic acids, phospholipids, fatty acids, bile acids, and gut flora metabolism, in HCC patients. Canavaninosuccinate was first identified as a metabolite that exhibited a significant decrease in LC and an increase in HCC. In addition, glycochenodeoxycholic acid was suggested to be an important indicator for HCC diagnosis and disease prognosis. UPLC-MS signatures, alone or in combination with AFP levels, could be an efficient and convenient tool for early diagnosis and screening of HCC in high-risk populations.

Linkage of gut microbiome with cognition in hepatic encephalopathy

Hepatic encephalopathy (HE) has been related to gut bacteria and inflammation in the setting of intestinal barrier dysfunction. We aimed to link the gut microbiome with cognition and inflammation in HE using a systems biology approach. Multitag pyrosequencing (MTPS) was performed on stool of cirrhotics and age-matched controls. Cirrhotics with/without HE underwent cognitive testing, inflammatory cytokines, and endotoxin analysis. Patients with HE were compared with those without HE using a correlation-network analysis. A select group of patients with HE (n = 7) on lactulose underwent stool MTPS before and after lactulose withdrawal over 14 days. Twenty-five patients [17 HE (all on lactulose, 6 also on rifaximin) and 8 without HE, age 56 ± 6 yr, model for end-stage liver disease score 16 ± 6] and ten controls were included. Fecal microbiota in cirrhotics were significantly different (higher Enterobacteriaceae, Alcaligeneceae, and Fusobacteriaceae and lower Ruminococcaceae and Lachnospiraceae) compared with controls. We found altered flora (higher Veillonellaceae), poor cognition, endotoxemia, and inflammation (IL-6, TNF-α, IL-2, and IL-13) in HE compared with cirrhotics without HE. In the cirrhosis group, Alcaligeneceae and Porphyromonadaceae were positively correlated with cognitive impairment. Fusobacteriaceae, Veillonellaceae, and Enterobacteriaceae were positively and Ruminococcaceae negatively related to inflammation. Network-analysis comparison showed robust correlations (all P < 1E-5) only in the HE group between the microbiome, cognition, and IL-23, IL-2, and IL-13. Lactulose withdrawal did not change the microbiome significantly beyond Fecalibacterium reduction. We concluded that cirrhosis, especially when complicated with HE, is associated with significant alterations in the stool microbiome compared with healthy individuals. Specific bacterial families (Alcaligeneceae, Porphyromonadaceae, Enterobacteriaceae) are strongly associated with cognition and inflammation in HE.

Role of innate immunity and the microbiota in liver fibrosis: crosstalk between the liver and gut

Liver fibrosis occurs as a wound-healing scar response following chronic liver inflammation including alcoholic liver disease, non-alcoholic steatohepatitis, viral hepatitis, cholestatic liver disease and autoimmune liver diseases. The liver has a unique vascular system within the gastrointestinal tract, as the majority of the liver's blood supply comes from the intestine through the portal vein. When the intestinal barrier function is disrupted, an increase in intestinal permeability leads to the translocation of intestine-derived bacterial products such as lipopolysaccharide (LPS) and unmethylated CpG containing DNA to the liver via the portal vein. These gut-derived bacterial products stimulate innate immune receptors, namely Toll-like receptors (TLRs), in the liver. TLRs are expressed on Kupffer cells, endothelial cells, dendritic cells, biliary epithelial cells, hepatic stellate cells, and hepatocytes. TLRs activate these cells to contribute to acute and chronic liver diseases. This review summarizes recent studies investigating the role of TLRs, intestinal microbiota and bacterial translocation in liver fibrosis, alcoholic liver disease and non-alcoholic steatohepatitis.