Endotoxemia in patients with chronic liver diseases: relationship to severity of liver diseases, presence of esophageal varices, and hyperdynamic circulation

Intrahepatic CD206+ macrophages contribute to inflammation in advanced viral-related liver disease

BACKGROUND & AIMS

Liver inflammation is key in the progression of chronic viral hepatitis to cirrhosis and hepatocellular carcinoma. The magnitude of viral replication and the specific anti-viral immune responses should govern the degree of inflammation, but a direct correlation is not consistently found in chronic viral hepatitis patients. We aim to better define the mechanisms that contribute to chronic liver inflammation.

METHODS

Intrahepatic CD14⁺ myeloid cells from healthy donors (n=19) and patients with viral-related liver cirrhosis (HBV, HBV/HDV or HCV; n=15) were subjected to detailed phenotypic, molecular and functional characterisation.

RESULTS

Unsupervised analysis of multi-parametric data showed that liver disease was associated with the intrahepatic expansion of activated myeloid cells mainly composed of pro-inflammatory CD14⁺HLA-DR^hiCD206⁺ cells, which spontaneously produced TNFα and GM-CSF. These cells only showed heightened pro-inflammatory responses to bacterial TLR agonists and were more refractory to endotoxin-induced tolerance. A liver-specific enrichment of CD14⁺HLA-DR^hiCD206⁺ cells was also detected in a humanised mouse model of liver inflammation. This accumulation was abrogated following oral antibiotic treatment, suggesting a direct involvement of translocated gut-derived microbial products in liver injury.

CONCLUSIONS

Viral-related chronic liver inflammation is driven by the interplay between non-endotoxin-tolerant pro-inflammatory CD14⁺HLA-DR^hiCD206⁺ myeloid cells and translocated bacterial products. Deciphering this mechanism paves the way for the development of therapeutic strategies specifically targeting CD206⁺ myeloid cells in viral-related liver disease patients. Lay summary: Viral-related chronic liver disease is driven by intrahepatic pro-inflammatory myeloid cells accumulating in a gut-derived bacterial product-dependent manner. Our findings support the use of oral antibiotics to ameliorate liver inflammation in these patients.

Review article: recent insights into clinical decision-making in severe alcoholic hepatitis

BACKGROUND

Alcoholic hepatitis is a severe acute manifestation of alcoholic liver disease with a high mortality. Management of patients with this condition has been a matter of controversy for many years; however, recent clinical studies have sought to improve the clinical approach to these patients.

AIM

To use these recent studies in order to guide clinical management.

METHODS

A MeSH search of Medline was performed to specifically identify recent studies which influenced clinical diagnosis, assessment and management of alcoholic hepatitis.

RESULTS

Fulfilment of clear clinical criteria including a minimum threshold of bilirubin, defined periods of jaundice and alcohol ingestion negates the need for liver biopsy in most patients. Corticosteroids improve short-term mortality only (28 day) with other factors such as abstinence likely to be significant in long-term outcome. Pentoxifylline is not an effective treatment. The Glasgow Alcoholic Hepatitis Score (GAHS) score can identify those patients likely to benefit from corticosteroids, but scores that include the evolution of bilirubin over 1 week of such treatment (such as the Lille Score) define "response". Underlying infection may contribute towards corticosteroid nonresponse and needs to be actively sought out and treated. Liver transplant remains controversial; however, it has been shown to be feasible in alcoholic hepatitis.

CONCLUSIONS

Recent studies have helped to define patients who may benefit from corticosteroid treatment. However, there remains a need for more accurate scores of prognosis and treatment response, and a clear need for alternative treatments for those patients not responding to corticosteroid therapy.

Bacterial translocation markers in liver cirrhosis

Bacterial translocation (BT) is an important mechanism in the development of infection in liver cirrhosis. The migration and colonization of bacteria and/or bacterial products from the bowel to mesenteric lymph nodes is a controlled process in healthy persons. Increased intestinal permeability, bacterial overgrowth and defect of gut-associated lymphatic tissue promote impaired BT in cirrhotics. We reviewed the reports on markers used for the evaluation of BT published between 1987 and 2016. We focused on the clinical consequences of BT in cirrhosis, as indicated by the values of the BT markers. Patients with cirrhosis are reported to have elevated levels of surrogate markers associated with BT compared with controls. The most widely used BT parameters are C-reactive protein, procalcitonin, bacterial DNA, endotoxin or lipopolysaccharide, lipopolysaccharide binding protein, calprotectin, and bactericidal/permeability increasing protein. High levels of these factors in serum and/or ascitic fluid in humans may be associated with advanced liver disease, hemodynamic instability, high levels of proinflammatory cytokines, susceptibility to the development of severe or recurrent infections, acute-on-chronic liver failure, hepatic encephalopathy, hepatorenal syndrome and poor prognosis during follow up. In conclusion, high levels of BT markers are associated with a high inflammatory response, increased complications of liver cirrhosis and occasionally high fatality rates.

Lipopolysaccharides induce Smad2 phosphorylation through PI3K/Akt and MAPK cascades in HSC-T6 hepatic stellate cells

AIMS

Endotoxemia and its pro-fibrogenic signaling play a significant role in the development of hepatic fibrosis. This study investigated whether lipopolysaccharide (LPS) directly activate cultured HSC-T6 hepatic stellate cells (HSCs) through triggering Smad-dependent pro-fibrogenic signaling pathway.

MAIN METHODS

Direct cell counting and assays for cell proliferation and migration were used to measure the effects of LPS on HSC behaviors. Quantitative PCR, Western blot, and gelatin zymography were used to quantify the molecular effects of LPS on expression of HSC activation markers and signaling activity.

KEY FINDINGS

Long-term exposure to LPS exhibited moderately stimulatory effect on HSC cell growth. A wound-healing cell migration assay showed that LPS suppressed HSC-T6 cell migration. qPCR and Western blotting detection indicated that LPS treatment induced upregulation of type I and IV collagens, α-smooth muscle actin (α-SMA), and matrix metalloproteinase-9 (MMP-9). Gelatin zymography confirmed that LPS elevated MMP-9, but not MMP-2 gelatinolytic activity. Moreover, LPS immediately stimulated Akt, EKR1/2, JNK, p38 MAPK, and Smad2 hyperphosphorylation, supporting that LPS directly triggers pro-fibrogenic Smad signaling cascade without TGF-β1 stimulation. Kinase blockade experiments demonstrated the involvement of PI3K/Akt, JNK, p38 MAPK, but not ERK1/2 signaling activation in the LPS-elicited Smad2 phosphorylation as well as the overexpression of type I collagen and α-SMA in HSC-T6 cells.

SIGNIFICANCE

These findings demonstrate that LPS exerts pro-fibrogenic effect through activation and transformation of HSCs. The tissue-remodeling effect of LPS may be attributable to its ability to activate non-canonical Smad pathway through PI3K/Akt and MAPK signaling cascades.

Rifaximin has no effect on hemodynamics in decompensated cirrhosis: A randomized, double-blind, placebo-controlled trial

Decompensated cirrhosis is characterized by disturbed systemic and splanchnic hemodynamics. Bacterial translocation from the gut is considered the key driver in this process. Intestinal decontamination with rifaximin may improve hemodynamics. This double-blind, randomized, controlled trial (clinicaltrials.gov, NCT01769040) investigates the effects of rifaximin on hemodynamics, renal function, and vasoactive hormones. We randomized 54 stable outpatients with cirrhosis and ascites to rifaximin 550 mg twice a day (n = 36) or placebo twice a day (n = 18). Forty-five patients were male, mean age 56 years (±8.4), average Child score 8.3 (±1.3), and Model for End-Stage Liver Disease score 11.7 (±3.9). Measurements of hepatic venous pressure gradient, cardiac output, and systemic vascular resistance were made at baseline and after 4 weeks. The glomerular filtration rate and plasma renin, noradrenaline, lipopolysaccharide binding protein, troponin T, and brain natriuretic peptide levels were measured. Rifaximin had no effect on hepatic venous pressure gradient, mean 16.8 ± 3.8 mm Hg at baseline versus 16.6 ± 5.3 mm Hg at follow-up, compared to the placebo, mean 16.4 ± 4 mm Hg at baseline versus 16.3 ± 4.4 mm Hg at follow-up, P = 0.94. No effect was found on cardiac output, mean 6.9 ± 1.7 L/min at baseline versus 6.9 ± 2.3 L/min at follow-up, compared to placebo, mean 6.6 ± 1.9 L/min at baseline compared to 6.5 ±2.1 L/min at follow-up, P = 0.66. No effects on the glomerular filtration rate, P = 0.14, or vasoactive hormones were found. Subgroup analyses on patients with increased lipopolysaccharide binding protein and systemic vascular resistance below the mean (1,011 dynes × s/cm⁵ ) revealed no effect of rifaximin.

CONCLUSION

Four weeks of treatment with rifaximin did not reduce the hepatic venous pressure gradient or improve systemic hemodynamics in patients with cirrhosis and ascites; rifaximin did not affect glomerular filtration rate or levels of vasoactive hormones. (Hepatology 2017;65:592-603).

Immune function biomarker QuantiFERON-monitor is associated with infection risk in cirrhotic patients

AIM

To investigate whether a novel immune function biomarker QuantiFERON-Monitor (QFM) can identify cirrhotic patients at greatest risk of infection.

METHODS

Adult cirrhotic patients on the liver transplant waiting list were recruited for this observational cohort study from a tertiary liver transplant referral unit. The immune function biomarker, QFM was performed using the same method as the widely available Quantiferon-gold assay, and measures output in interferon gamma in IU/mL after dual stimulation of the innate and adaptive immune systems. Ninety-one cirrhotic patients were recruited, with 47 (52%) transplanted on the day of their QFM. The remaining 44 (48%) were monitored for infections until transplant, death, or census date of 1st February 2014.

RESULTS

Cirrhotic patients express a median QFM significantly lower than healthy controls (94.5 IU/mL vs 423 IU/mL), demonstrating that they are severely immunosuppressed. Several factors including model for end stage liver disease, presence of hepatocellular carcinoma, bilirubin, international normalized ratio and haemoglobin were associated with QFM on univariate analysis. Disease aetiology did not appear to impact QFM. On multivariate analysis, only Child-Pugh score and urea were significantly associated with a patient's immune function as objectively measured by QFM. In the 44 patients who were not transplanted immediately after their blood test and could be monitored for subsequent infection risk, 13 (29.5%) experienced a pre-transplant infection a median 20 d (range 2-182) post-test. QFM < 214 IU/mL was associated with HR = 4.1 (P = 0.01) for infection. A very low QFM < 30 IU/mL was significantly associated (P = 0.003) with death in three patients who died while awaiting transplantation (HR = 56.6).

CONCLUSION

QFM is lower in cirrhotics, allowing objective determinations of an individual's unique level of immune dysfunction. Low QFM was associated with increased susceptibility to infection.

Non-selective β-blockers in advanced cirrhosis: a critical review of the effects on overall survival and renal function

INTRODUCTION

Non-selective β-blockers (NSBBs) are widely prescribed in patients with cirrhosis for primary and secondary prophylaxis of bleeding oesophageal varices. Furthermore, it has been suggested that the clinical benefits of NSBBs may extend beyond their haemodynamic effects. Recently, a potentially harmful effect has been described in patients with refractory ascites or spontaneous bacterial peritonitis.

METHODOLOGY

A comprehensive literature search on β-blockers and cirrhosis survival using the electronic databases PubMed/MEDLINE, AMED, CINAHL and the Cochrane Central Register of Controlled Trials. Full-text manuscripts published over more than 35 years, from 1980 to April 2016 were reviewed for relevance and reference lists were cross-checked for additional pertinent studies regarding potential NSBB effects, especially focused on those concerned with survival and/or acute kidney injury (AKI).

DISCUSSION

The proposed review will be able to provide valuable evidence to help decision making in the use of NSBB for the treatment of advanced cirrhosis and highlights some limitations in existing evidence to direct future research.

Rifaximin Decreases the Incidence and Severity of Acute Kidney Injury and Hepatorenal Syndrome in Cirrhosis

BACKGROUND

While the effects of rifaximin have been shown to be protective against acute kidney injury (AKI) and hepatorenal syndrome (HRS) in alcohol-induced cirrhosis, its long-term effects on the renal function of other cirrhotic patients are unknown.

AIM

To examine the long-term effects of rifaximin on the renal function of patients with cirrhosis from various etiologies.

METHODS

In a retrospective study, we examined cirrhotic patients at the University of Chicago Liver Clinic from January 1, 2011, to December 31, 2014. The study enrolled patients on rifaximin for ≥90 days, who were then matched by age, gender, and MELD score to a control group. Patients with malignancy and renal replacement therapy (RRT) at baseline were excluded. Data were censored at the last follow-up, termination of rifaximin therapy, initiation of RRT, death, or liver transplant.

RESULTS

Eighty-eight rifaximin cases were identified and matched to 88 control cases. Baseline characteristics were similar, with the exceptions of more prevalent long-term midodrine use (≥90 days) (17.0 vs 4.5 %, p = 0.01) and baseline ascites (37.5 vs 23.8 %, p = 0.05) in the rifaximin group. There was no difference in the frequency of infections, deaths, liver transplants, or hospitalizations. After controlling for cofounders, the incidence rate ratio of AKI (IRR 0.71, p = 0.02) and HRS (IRR 0.21, p = 0.02), as well as the risk of requiring RRT (OR 0.23, p = 0.01), was lower in the rifaximin group.

CONCLUSIONS

Long-term use of rifaximin is associated with a decrease incidence of AKI and HRS and a decrease risk of requiring RRT in a general population of cirrhotic patients.

Increased EMR2 expression on neutrophils correlates with disease severity and predicts overall mortality in cirrhotic patients

Patients with liver cirrhosis are susceptible to infections with high short-term mortalities. One CD97-related EGF-TM7 molecule, EMR2 (EGF-like molecule containing mucin-like hormone receptor 2), had been shown to regulate human neutrophil function, potentiate systemic inflammation. Nevertheless, EMR2 could also suppress neutrophil survival. Studying the role of EMR2 on neutrophil would be intriguing. 48 healthy volunteers and 100 cirrhotic patients were enrolled. Neutrophils were isolated from peripheral blood and cell surface markers were measured by flow cytometry.EMR2 expression levels correlated with CTP scores and increased further in patients with infections. These EMR2-expressed neutrophils were with activated phenotype, but with deranged functions like increased resting oxidative burst and impaired phagocytosis ability. Ligation of EMR2 could increase the phagoburst capacity but not the phagocytosis ability. Furthermore, neutrophils with higher EMR2 expression were more apoptotic and lost the LPS-induced neutrophil survival. Finally, EMR2 expressions on neutrophils correlated with infections and their levels greater than 25 had an AUC = 0.708 for predicting mortality. In conclusion, EMR2 expression levels correlated with CTP scores and increased further in cirrhotic patients with infections. These high EMR2-expressed neutrophils had activated phenotype but with deranged functions. Higher levels of these EMR2-expressed neutrophils correlated with infectious complications and predict mortality.

Factoring the intestinal microbiome into the pathogenesis of autoimmune hepatitis

The intestinal microbiome is a reservoir of microbial antigens and activated immune cells. The aims of this review were to describe the role of the intestinal microbiome in generating innate and adaptive immune responses, indicate how these responses contribute to the development of systemic immune-mediated diseases, and encourage investigations that improve the understanding and management of autoimmune hepatitis. Alterations in the composition of the intestinal microflora (dysbiosis) can disrupt intestinal and systemic immune tolerances for commensal bacteria. Toll-like receptors within the intestine can recognize microbe-associated molecular patterns and shape subsets of T helper lymphocytes that may cross-react with host antigens (molecular mimicry). Activated gut-derived lymphocytes can migrate to lymph nodes, and gut-derived microbial antigens can translocate to extra-intestinal sites. Inflammasomes can form within hepatocytes and hepatic stellate cells, and they can drive the pro-inflammatory, immune-mediated, and fibrotic responses. Diet, designer probiotics, vitamin supplements, re-colonization methods, antibiotics, drugs that decrease intestinal permeability, and molecular interventions that block signaling pathways may emerge as adjunctive regimens that complement conventional immunosuppressive management. In conclusion, investigations of the intestinal microbiome are warranted in autoimmune hepatitis and promise to clarify pathogenic mechanisms and suggest alternative management strategies.

LPS-induced TNF-α factor mediates pro-inflammatory and pro-fibrogenic pattern in non-alcoholic fatty liver disease

Lipopolysaccharide (LPS) is currently considered one of the major players in non-alcoholic fatty liver disease (NAFLD) pathogenesis and progression. Here, we aim to investigate the possible role of LPS-induced TNF-α factor (LITAF) in inducing a pro-inflammatory and pro-fibrogenic phenotype of non-alcoholic steatohepatitis (NASH).We found that children with NAFLD displayed, in different liver-resident cells, an increased expression of LITAF which correlated with histological traits of hepatic inflammation and fibrosis. Total and nuclear LITAF expression increased in mouse and human hepatic stellate cells (HSCs). Moreover, LPS induced LITAF-dependent transcription of IL-1β, IL-6 and TNF-α in the clonal myofibroblastic HSC LX-2 cell line, and this effect was hampered by LITAF silencing. We showed, for the first time in HSCs, that LITAF recruitment to these cytokine promoters is LPS dependent. However, preventing LITAF nuclear translocation by p38MAPK inhibitor, the expression of IL-6 and TNF-α was significantly reduced with the aid of p65NF-ĸB, while IL-1β transcription exclusively required LITAF expression/activity. Finally, IL-1β levels in plasma mirrored those in the liver and correlated with LPS levels and LITAF-positive HSCs in children with NASH.In conclusion, a more severe histological profile in paediatric NAFLD is associated with LITAF over-expression in HSCs, which in turn correlates with hepatic and circulating IL-1β levels outlining a panel of potential biomarkers of NASH-related liver damage. The in vitro study highlights the role of LITAF as a key regulator of the LPS-induced pro-inflammatory pattern in HSCs and suggests p38MAPK inhibitors as a possible therapeutic approach against hepatic inflammation in NASH.

Microbiome and Anticancer Immunosurveillance

Anticancer immune responses can be considered a desirable form of autoimmunity that may be profoundly shaped by the microbiome. Here, we discuss evidence for the microbiome's influence on anti-tumor immunosurveillance, including those that are indirect and can act at a distance, and we put forward hypotheses regarding mechanisms of how these effects are implemented. These may involve cross-reactivity between microbial and tumor antigens shaping T cell repertoires and/or microbial products stimulating pattern recognition receptors that influence the type and intensity of immune responses. Understanding how the microbiome impacts natural cancer immunosurveillance as well as treatment-induced immune responses will pave the way for more effective therapies and prophylactics.

Identifying Novel Targets for Treatment of Liver Fibrosis: What Can We Learn from Injured Tissues which Heal Without a Scar?

The liver is unique in that it is able to regenerate. This regeneration occurs without formation of a scar in the case of non-iterative hepatic injury. However, when the liver is exposed to chronic liver injury, the purely regenerative process fails and excessive extracellular matrix proteins are deposited in place of normal liver parenchyma. While much has been discovered in the past three decades, insights into fibrotic mechanisms have not yet lead to effective therapies; liver transplant remains the only cure for advanced liver disease. In an effort to broaden the collection of possible therapeutic targets, this review will compare and contrast the liver wound healing response to that found in two types of wound healing: scarless wound healing of fetal skin and oral mucosa and scar-forming wound healing found in adult skin. This review will examine wound healing in the liver and the skin in relation to the role of humoral and cellular factors, as well as the extracellular matrix, in this process. While several therapeutic targets are similar between fibrotic liver and adult skin wound healing, others are unique and represent novel areas for hepatic anti-fibrotic research. In particular, investigations into the role of hyaluronan in liver fibrosis and fibrosis resolution are warranted.

Alcoholic liver disease: the gut microbiome and liver cross talk

Alcoholic liver disease (ALD) is a leading cause of morbidity and mortality worldwide. Alcoholic fatty liver disease can progress to steatohepatitis, alcoholic hepatitis, fibrosis, and cirrhosis. Patients with alcohol abuse show quantitative and qualitative changes in the composition of the intestinal microbiome. Furthermore, patients with ALD have increased intestinal permeability and elevated systemic levels of gut-derived microbial products. Maintaining eubiosis, stabilizing the mucosal gut barrier, or preventing cellular responses to microbial products protect from experimental ALD. Therefore, intestinal dysbiosis and pathological bacterial translocation appear fundamental for the pathogenesis of ALD. This review highlights causes for intestinal dysbiosis and pathological bacterial translocation, their relationship, and consequences for ALD. We also discuss how the liver affects the intestinal microbiota.

The pathophysiology of thrombocytopenia in chronic liver disease

Thrombocytopenia is the most common hematological abnormality encountered in patients with chronic liver disease (CLD). In addition to being an indicator of advanced disease and poor prognosis, it frequently prevents crucial interventions. Historically, thrombocytopenia has been attributed to hypersplenism, which is the increased pooling of platelets in a spleen enlarged by congestive splenomegaly secondary to portal hypertension. Over the past decade, however, there have been significant advances in the understanding of thrombopoiesis, which, in turn, has led to an improved understanding of thrombocytopenia in cirrhosis. Multiple factors contribute to the development of thrombocytopenia and these can broadly be divided into those that cause decreased production, splenic sequestration, and increased destruction. Depressed thrombopoietin levels in CLD, together with direct bone marrow suppression, result in a reduced rate of platelet production. Thrombopoietin regulates both platelet production and maturation and is impaired in CLD. Bone marrow suppression can be caused by viruses, alcohol, iron overload, and medications. Splenic sequestration results from hypersplenism. The increased rate of platelet destruction in cirrhosis also occurs through a number of pathways: increased shear stress, increased fibrinolysis, bacterial translocation, and infection result in an increased rate of platelet aggregation, while autoimmune disease and raised titers of antiplatelet immunoglobulin result in the immunologic destruction of platelets. An in-depth understanding of the complex pathophysiology of the thrombocytopenia of CLD is crucial when considering treatment strategies. This review outlines the recent advances in our understanding of thrombocytopenia in cirrhosis and CLD.

Beneficial effect of refined red palm oil on lipid peroxidation and monocyte tissue factor in HCV-related liver disease: a randomized controlled study

BACKGROUND

A large amount of endotoxin can be detected in the peripheral venous blood of patients with liver cirrhosis, contributing to the pathogenesis of hepatotoxicity because of its role in oxidative stress. The present study aimed to test the effect of the supplementation with red palm oil (RPO), which is a natural oil obtained from oil palm fruit (Elaeis guineensis) rich in natural fat-soluble tocopherols, tocotrienols and carotenoids, on lipid peroxidation and endotoxemia with plasma endotoxin-inactivating capacity, proinflammatory cytokines profile, and monocyte tissue factor in patients with chronic liver disease.

METHODS

The study group consisted of sixty patients (34 males and 26 females; mean age 62 years, range 54-75) with Child A/B, genotype 1 HCV-related cirrhosis without a history of ethanol consumption, randomly enrolled into an 8-week oral daily treatment with either vitamin E or RPO. All patients had undergone an upper gastrointestinal endoscopy 8 months before, and 13 out of them showed esophageal varices.

RESULTS

Both treatments significantly decreased erythrocyte malondialdehyde and urinary isoprostane output, only RPO significantly affected macrophage-colony stimulating factor and monocyte tissue factor. Liver ultrasound imaging did not show any change.

CONCLUSIONS

RPO beneficially modulates oxidative stress and, not least, downregulates macrophage/monocyte inflammatory parameters. RPO can be safely advised as a valuable nutritional implementation tool in the management of chronic liver diseases.

Intestinal Fibrosis and Liver Fibrosis: Consequences of Chronic Inflammation or Independent Pathophysiology?

Background

Intestinal fibrosis and liver fibrosis represent a significant burden for our patients and health-care systems. Despite the severe clinical problem and the observation that fibrosis is reversible, no specific antifibrotic therapies exist.

Summary

In this review, using an 'East-West' scientific collaboration, we summarize the current knowledge on principal mechanisms shared by intestinal fibrosis and liver fibrosis. We furthermore discuss inflammation as the cause of fibrogenesis in both entities, depict unique features of intestinal and hepatic fibrosis, and provide a future outlook on the development of antifibrotic therapies.

Key Messages

A collaborative effort in the field of fibrosis, covering multiple organ systems, will have the highest chance of leading to the development of a successful antifibrotic intervention.

Intestinal microbiota in liver disease

The intestinal microbiota have emerged as a topic of intense interest in gastroenterology and hepatology. The liver is on the front line as the first filter of nutrients, toxins and bacterial metabolites from the intestines and we are becoming increasingly aware of interactions among the gut, liver and immune system as important mediators of liver health and disease. Manipulating the microbiota with therapeutic intent is a rapidly expanding field. In this review, we will describe what is known about the contribution of intestinal microbiota to liver homeostasis; the role of dysbiosis in the pathogenesis of liver disease including alcoholic and non-alcoholic fatty liver disease, cirrhosis and hepatocellular carcinoma; and the therapeutic manifestations of altering intestinal microbiota via antibiotics, prebiotics, probiotics and fecal microbiota transplantation.

Chasing a ghost?--Issues with the determination of circulating levels of endotoxin in human blood

Reliable quantification of bacterial products such as endotoxin is important for the diagnosis of Gram-negative infection and for the monitoring of its treatment. Further, it is important to identify patients with persistent subclinical level of bacterial products in their systemic circulation as data from animal studies also suggest this may be correlated with the onset of metabolic syndrome. In this review, we first aim to describe the principles of the Limulus amoebocyte lysate (LAL) test, an assay that is used to quantify endotoxin, and the various shortcomings that must be addressed before it can become a reliable means of quantifying endotoxin in samples derived from blood. We then review published data regarding endotoxin levels in healthy subjects and those with sepsis, inflammatory bowel disease, liver disorders and metabolic disorders such as obesity and diabetes. We also review the evidence regarding influence of macronutrients in augmenting the levels of systemic endotoxin. The results of this review show that reported mean levels of endotoxin in the systemic circulation of healthy humans and of those with various clinical disorders vary over a wide range. Further, this review shows that a significant proportion of this variation can be related to the method that was used to prepare plasma and serum samples prior to assay and its ability to reduce the effect of various blood borne factors that interfere with the LAL assay.

A variant in the nuclear dot protein 52kDa gene increases the risk for spontaneous bacterial peritonitis in patients with alcoholic liver cirrhosis

BACKGROUND

Spontaneous bacterial peritonitis is frequently a fatal infection in patients with liver cirrhosis. We investigated if nuclear dot protein 52kDa (NDP52), a negative regulator of toll-like receptor (TLR) signalling and autophagy adaptor protein, might be involved.

METHODS

Two cohorts comprising 152 (derivation cohort) and 198 patients (validation cohort) with decompensated liver cirrhosis and 168 healthy controls were genotyped for the rs2303015 polymorphism in the NDP52 gene and prospectively followed-up for spontaneous bacterial peritonitis.

RESULTS

Overall, 57 (38%) patients in the derivation cohort and 77 (39%) in the validation cohort had spontaneous bacterial peritonitis. Cirrhosis was due to alcohol abuse in 57% of the derivation and 66% of the validation cohort. In patients with alcoholic cirrhosis, patients with spontaneous bacterial peritonitis had an increased frequency of the NDP52 rs2303015 minor variant in the derivation (p=0.04) and in the validation cohort (p=0.01). Multivariate analysis confirmed this minor variant (odds ratio 4.7, p=0.002) and the TLR2 -16934 TT variant (odds ratio 2.5, p=0.008) as risk factors for spontaneous bacterial peritonitis. In addition, presence of the NDP52 minor variant affected survival negatively.

CONCLUSION

Presence of the NDP52 rs2303015 minor variant increases the risk for spontaneous bacterial peritonitis in patients with alcoholic cirrhosis.

Targeting gut-liver axis for the treatment of nonalcoholic steatohepatitis: translational and clinical evidence

Nonalcoholic fatty liver disease (NAFLD) is widely emerging as the most prevalent liver disorder and is associated with increased risk of liver-related and cardiovascular mortality. Recent experimental and clinical studies have revealed the pivotal role played by the alteration of gut-liver axis in the onset of fatty liver and related metabolic disturbances. Gut-liver cross talk is implicated not only in the impairment of lipid and glucose homeostasis leading to steatogenesis, but also in the initiation of inflammation and fibrogenesis, which characterize nonalcoholic steatohepatitis (NASH), the evolving form of NAFLD. The gut microbiota has been recognized as the key player in the gut-liver liaison and because of its complexity can act as a villain or a victim. Gut microbiota not only influences absorption and disposal of nutrients to the liver, but also conditions hepatic inflammation by supplying toll-like receptor ligands, which can stimulate liver cells to produce proinflammatory cytokines. Thus, the modification of intestinal bacterial flora by specific probiotics has been proposed as a therapeutic approach for the treatment of NASH. In this review, we summarized the evidence regarding the role of gut-liver axis in the pathogenesis of NASH and discussed the potential therapeutic role of gut microbiota modulation in the clinical setting.

Alcoholic hepatitis and HCV interactions in the modulation of liver disease

Most HCV-infected patients regularly consume alcohol. Alcoholic liver disease (ALD) and chronic hepatitis C virus (HCV) infection together are the most common causes of liver disease worldwide. Although both factors independently cause liver disease, they synergistically promote rapid liver disease progression with devastating outcomes for patients. This review focuses on the prevalence, clinical characteristics and molecular pathophysiologic mechanisms of HCV infection associated with alcohol abuse. Recent findings have centred on the synergistic effect of alcohol and HCV on viral replication, hepatocyte apoptosis, oxidative stress, alcohol-induced 'leaky gut', miR-122 and immune dysregulation. Clinical and basic research findings presented here summarize key scientific findings with the aim of highlighting potential areas for new therapies and identifying ways of optimizing current treatments for alcoholics with HCV infection.

Liver injury is associated with mortality in sickle cell disease

BACKGROUND

Increased life expectancy in sickle cell disease (SCD) has resulted in greater recognition of the consequences of repeated intravascular vaso-occlusion and chronic haemolysis to multiple organ systems.

AIM

To report the long-term consequences of liver dysfunction in SCD.

METHODS

A cohort of SCD patients was prospectively evaluated at the National Institutes of Health (NIH) Clinical Center. The association of mortality with liver enzymes, parameters of liver synthetic function and iron overload was evaluated using Cox regression.

RESULTS

Exactly, 247 SCD patients were followed up for 30 months of whom 22 (9%) died. After controlling for predictors, increased direct bilirubin (DB), ferritin, alkaline phosphatase and decreased albumin were independently associated with mortality. In a multivariable model, only high DB and ferritin remained significant. Ferritin correlated with hepatic iron content and total blood transfusions but not haemolysis markers. Forty patients underwent liver biopsies and 11 (28%) had fibrosis. Twelve of 26 patients (48%) had portal hypertension by hepatic venous pressure gradient (HVPG) measurements. All patients with advanced liver fibrosis had iron overload; however, most patients (69%) with iron overload were without significant hepatic fibrosis. Ferritin did not correlate with left ventricular dysfunction by echocardiography. DB correlated with bile acid levels suggesting liver pathology. Platelet count and soluble CD14 correlated with HVPG indicating portal hypertension.

CONCLUSIONS

Ferritin and direct bilirubin are independently associated with mortality in sickle cell disease. Ferritin likely relates to transfusional iron overload, while direct bilirubin suggests impairment of hepatic function, possibly impairing patients' ability to tolerate systemic insults.

Markers of bacterial translocation in end-stage liver disease

Bacterial translocation (BT) refers to the passage of viable bacteria or bacterial products from the intestinal lumen, through the intestinal epithelium, into the systemic circulation and extraintestinal locations. The three principal mechanisms that are thought to be involved in BT include bacterial overgrowth, disruption of the gut mucosal barrier and an impaired host defence. BT is commonly observed in liver cirrhosis and has been shown to play an important role in the pathogenesis of the complications of end stage liver disease, including infections as well as hepatic encephalopathy and hepatorenal syndrome. Due to the importance of BT in the natural history of cirrhosis, there is intense interest for the discovery of biomarkers of BT. To date, several such candidates have been proposed, which include bacterial DNA, soluble CD14, lipopolysaccharides endotoxin, lipopolysaccharide-binding protein, calprotectin and procalcitonin. Studies on the association of these markers with BT have demonstrated not only promising data but, oftentimes, contradictory results. As a consequence, currently, there is no optimal marker that may be used in clinical practice as a surrogate for the presence of BT.

Upregulated Expression of A20 on Monocytes is Associated With Increased Severity of Acute-on-Chronic Hepatitis B Liver Failure: A Case-Control Study

A20 expression is increased in various inflammatory diseases. However, the role of A20 in acute-on-chronic liver failure is unknown. This study was to evaluate A20 expression on monocytes and its associations with the severity of acute-on-chronic hepatitis B liver failure (ACHBLF). Thirty-seven patients with ACHBLF, 20 patients with chronic hepatitis B (CHB), and 15 healthy controls (HC) were enrolled in this case-control study. A20-positive monocytes were identified using flow cytometry. Serum levels of interleukin (IL)-10, IL-12p70, and TNF-α were determined using bead cytometry. A20 and IL-10 expressions were examined in THP-1 cells stimulated by lipopolysaccharide (LPS). The frequency of A20+ monocytes was significantly increased in patients with ACHBLF compared with HC (median [interquartile range, IQR]: 15.7 [22.8]% vs 2.5 [4.7]%, P < 0.001). Increased monocyte A20 expression was detected during the progression phase (including the mild/moderate and severe grades of ACHBLF) compared with patients in the recovery phase (both P < 0.05), and in the ACHBLF worsening group compared with patients in the improvement group (P < 0.001). LPS treatment upregulated A20 and IL-10 expressions in THP-1 cells. A20 expression on monocytes from patients with ACHBLF was positively correlated with total bilirubin (r = 0.60, P = 0.0001), direct bilirubin (r = 0.63, P < 0.0001), and MELD score (r = 0.43, P = 0.008), and inversely with prothrombin activity (r = -0.33, P = 0.046). IL-10 and TLR4 expression levels in monocytes, and serum levels of IL-10, IL-12p70, and TNF-α were increased in patients with ACHBLF compared with patients with CHB and HC. Increased A20 expression on monocytes was associated with the severity of ACHBLF.

Artesunate alleviates hepatic fibrosis induced by multiple pathogenic factors and inflammation through the inhibition of LPS/TLR4/NF-κB signaling pathway in rats

The current study was performed in order to explore the effect of artesunate (Art) on experimental hepatic fibrosis and the potential mechanism involved. Art, a water-soluble hemisuccinate derivative of artemisinin extracted from the Chinese herb Artemisia Annua, is a safe and effective antimalarial drug. Hepatic fibrosis was induced in SD rats by multiple pathogenic factors. Rats were treated concurrently with Art (28.8 mg/kg) given daily by oral gavage for 6 or 8 weeks to evaluate its protective effects. Our data demonstrated that Art treatment obviously attenuated hepatic fibrosis, characterized by less inflammatory infiltration and accumulation of extracellular matrix (ECM). Art remarkably decreased endotoxin, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) levels as well. Art significantly downregulated protein and mRNA expression of α-smooth muscle actin (α-SMA), toll-like receptors 4 (TLR4), myeloid differentiation factor 88 (MyD88) and transforming growth factor beta 1 (TGF-β1). Art also significantly inhibited the nuclear transcription factor kappa B p65 (NF-κB p65) translocation into the nucleus. In addition, there were no remarkable differences between the N group and the NA group. In conclusion, we found that Art could alleviate hepatic fibrosis induced by multiple pathogenic factors and inflammation through the inhibition of LPS/TLR4/NF-κB signaling pathway in rats, suggesting that Art may be a potential candidate for the therapy of hepatic fibrosis.

Lipopolysaccharide and toll-like receptor 4 in dogs with congenital portosystemic shunts

Surgical attenuation of a congenital portosystemic shunt (CPSS) results in increased portal vein perfusion, liver growth and clinical improvement. Portal lipopolysaccharide (LPS) is implicated in liver regeneration via toll-like receptor (TLR) 4 mediated cytokine activation. The aim of this study was to investigate factors associated with LPS in dogs with CPSS. Plasma LPS concentrations were measured in the peripheral and portal blood using a limulus amoebocyte lysate (LAL) assay. LPS concentration was significantly greater in the portal blood compared to peripheral blood in dogs with CPSS (P = 0.046) and control dogs (P = 0.002). LPS concentrations in the peripheral (P = 0.012) and portal (P = 0.005) blood of dogs with CPSS were significantly greater than those of control dogs. The relative mRNA expression of cytokines and TLRs was measured in liver biopsies from dogs with CPSS using quantitative PCR. TLR4 expression significantly increased following partial CPSS attenuation (P = 0.020). TLR4 expression was significantly greater in dogs that tolerated complete CPSS attenuation (P = 0.011) and those with good portal blood flow on pre-attenuation (P = 0.004) and post-attenuation (P = 0.015) portovenography. Serum interleukin (IL)-6 concentration was measured using a canine specific ELISA and significantly increased 24 h following CPSS attenuation (P < 0.001). Portal LPS was increased in dogs with CPSS, consistent with decreased hepatic clearance. TLR4 mRNA expression was significantly associated with portal blood flow and increased following surgery. These findings support the concept that portal LPS delivery is important in the hepatic response to surgical attenuation. Serum IL-6 significantly increased following surgery, consistent with LPS stimulation via TLR4, although this increase might be non-specific.

Persistent Organic Pollutants Modify Gut Microbiota-Host Metabolic Homeostasis in Mice Through Aryl Hydrocarbon Receptor Activation

BACKGROUND

Alteration of the gut microbiota through diet and environmental contaminants may disturb physiological homeostasis, leading to various diseases including obesity and type 2 diabetes. Because most exposure to environmentally persistent organic pollutants (POPs) occurs through the diet, the host gastrointestinal tract and commensal gut microbiota are likely to be exposed to POPs.

OBJECTIVES

We examined the effect of 2,3,7,8-tetrachlorodibenzofuran (TCDF), a persistent environmental contaminant, on gut microbiota and host metabolism, and we examined correlations between gut microbiota composition and signaling pathways.

METHODS

Six-week-old male wild-type and Ahr-/- mice on the C57BL/6J background were treated with 24 μg/kg TCDF in the diet for 5 days. We used 16S rRNA gene sequencing, 1H nuclear magnetic resonance (NMR) metabolomics, targeted ultra-performance liquid chromatography coupled with triplequadrupole mass spectrometry, and biochemical assays to determine the microbiota compositions and the physiological and metabolic effects of TCDF.

RESULTS

Dietary TCDF altered the gut microbiota by shifting the ratio of Firmicutes to Bacteroidetes. TCDF-treated mouse cecal contents were enriched with Butyrivibrio spp. but depleted in Oscillobacter spp. compared with vehicle-treated mice. These changes in the gut microbiota were associated with altered bile acid metabolism. Further, dietary TCDF inhibited the farnesoid X receptor (FXR) signaling pathway, triggered significant inflammation and host metabolic disorders as a result of activation of bacterial fermentation, and altered hepatic lipogenesis, gluconeogenesis, and glycogenolysis in an AHR-dependent manner.

CONCLUSION

These findings provide new insights into the biochemical consequences of TCDF exposure involving the alteration of the gut microbiota, modulation of nuclear receptor signaling, and disruption of host metabolism.

Portal vein thrombosis in cirrhosis: Controversies and latest developments

Portal vein thrombosis (PVT) is encountered in liver cirrhosis, particularly in advanced disease. It has been a feared complication of cirrhosis, attributed to significant worsening of liver disease, poorer clinical outcomes and potential inoperability at liver transplantation; also catastrophic events such as acute intestinal ischaemia. Optimal management of PVT has not yet been addressed in any consensus publication. We review current literature on PVT in cirrhosis; its prevalence, pathophysiology, diagnosis, impact on the natural history of cirrhosis and liver transplantation, and management. Studies were identified by a search strategy using MEDLINE and Google Scholar. The incidence of PVT increases with increasing severity of liver disease: less than 1% in well-compensated cirrhosis, 7.4%-16% in advanced cirrhosis. Prevalence in patients undergoing liver transplantation is 5%-16%. PVT frequently regresses instead of uniform thrombus progression. PVT is not associated with increased risk of mortality. Optimal management has not been addressed in any consensus publication. We propose areas for future research to address unresolved clinical questions.

Liver fibrosis occurs through dysregulation of MyD88-dependent innate B-cell activity

Chronic liver disease mediated by activation of hepatic stellate cells (HSCs) leads to liver fibrosis. Here, we postulated that the immune regulatory properties of HSCs might promote the profibrogenic activity of B cells. Fibrosis is completely attenuated in carbon tetrachloride-treated, B cell-deficient µMT mice, showing that B cells are required. The retinoic acid produced by HSCs augmented B-cell survival, plasma cell marker CD138 expression, and immunoglobulin G production. These activities were reversed following addition of the retinoic acid inhibitor LE540. Transcriptional profiling of fibrotic liver B cells revealed increased expression of genes related to activation of nuclear factor κ light chain enhancer of activated B cells, proinflammatory cytokine production, and CD40 signaling, suggesting that these B cells are activated and may be acting as inflammatory cells. Biological validation experiments also revealed increased activation (CD44 and CD86 expression), constitutive immunoglobulin G production, and secretion of the proinflammatory cytokines tumor necrosis factor-α, monocyte chemoattractant protein-1, and macrophage inflammatory protein-1α. Likewise, targeted deletion of B-cell-intrinsic myeloid differentiation primary response gene 88 signaling, an innate adaptor with involvement in retinoic acid signaling, resulted in reduced infiltration of migratory CD11c(+) dendritic cells and Ly6C(++) monocytes and, hence, reduced liver pathology.

CONCLUSION

Liver fibrosis occurs through a mechanism of HSC-mediated augmentation of innate B-cell activity. These findings highlight B cells as important "first responders" of the intrahepatic immune environment.

Methods to determine intestinal permeability and bacterial translocation during liver disease

Liver disease is often times associated with increased intestinal permeability. A disruption of the gut barrier allows microbial products and viable bacteria to translocate from the intestinal lumen to extraintestinal organs. The majority of the venous blood from the intestinal tract is drained into the portal circulation, which is part of the dual hepatic blood supply. The liver is therefore the first organ in the body to encounter not only absorbed nutrients, but also gut-derived bacteria and pathogen associated molecular patterns (PAMPs). Chronic exposure to increased levels of PAMPs has been linked to disease progression during early stages and to infectious complications during late stages of liver disease (cirrhosis). It is therefore important to assess and monitor gut barrier dysfunction during hepatic disease. We review methods to assess intestinal barrier disruption and discuss advantages and disadvantages. We will in particular focus on methods that we have used to measure increased intestinal permeability and bacterial translocation in experimental liver disease models.

Gut-liver axis in liver cirrhosis: How to manage leaky gut and endotoxemia

A “leaky gut” may be the cutting edge for the passage of toxins, antigens or bacteria into the body, and may play a pathogenic role in advanced liver cirrhosis and its complications. Plasma endotoxin levels have been admitted as a surrogate marker of bacterial translocation and close relations of endotoxemia to hyperdynamic circulation, portal hypertension, renal, cardiac, pulmonary and coagulation disturbances have been reported. Bacterial overgrowth, increased intestinal permeability, failure to inactivate endotoxin, activated innate immunity are all likely to play a role in the pathological states of bacterial translocation. Therapeutic approach by management of the gut-liver axis by antibiotics, probiotics, synbiotics, prebiotics and their combinations may improve the clinical course of cirrhotic patients. Special concern should be paid on anti-endotoxin treatment. Adequate management of the gut-liver axis may be effective for prevention of liver cirrhosis itself by inhibiting the progression of fibrosis.

Low levels of microbial translocation marker LBP are associated with sustained viral response after anti-HCV treatment in HIV-1/HCV co-infected patients

BACKGROUND

Microbial translocation (MT) contributes to immune activation during HIV and HCV infections. We investigated the kinetics of MT markers during anti-HCV and anti-HIV treatments, and if baseline plasma levels of lipopolysaccharide (LPS), lipopolysaccharide binding protein (LBP) and soluble CD14 (sCD14) could predict anti-HCV treatment outcome.

METHODS

Plasma from 78 HIV-infected patients was evaluated for LPS, LBP and sCD14. The patients starting anti-HCV treatment (with ongoing antiretroviral (ART) treatment) were categorized into sustained viral responders (SVR; n = 21) or non-responders (NR; n = 15) based on treatment outcome. ART starting subjects--were categorized into chronically HCV-infected (CH; n = 24) and mono-infected (HIV; n = 18), based on the HCV infection status. Samples were collected before start (at baseline) of pegylated-interferon-alpha/ribavirin (peg-IFN/RBV) or antiretroviral-therapy and two years after treatment start (at follow up). χ2-test, non-parametric statistics and logistic regression were applied to determine the associations with treatment response and changes of the soluble markers.

RESULTS

Plasma levels of LPS and sCD14 were elevated in all subjects before antiviral-treatment but remained unchanged at follow-up. Elevated levels of LBP were present in patients with HIV and HIV/HCV co-infection and were reduced by ART. Additionally, higher levels of LBP were present at baseline in NR vs. SVR. Higher levels of LBP at baseline were associated with non-response to peg-IFN/RBV treatment in both bivariate (OR: 0.19 95% CI: 0.06-0.31, p = 0.004) and multivariate analysis (OR: 1.43, 95% CI: 1.1-1.86, p = 0.07).

CONCLUSION

In HIV/HCV co-infected patients high baseline LBP levels are associated with non-response to peg-IFN/RBV therapy. Plasma LBP (decreased by ART) may be a more relevant MT marker than LPS and sCD14.

Attenuation of congenital portosystemic shunt reduces inflammation in dogs

Liver disease is a major cause of morbidity and mortality. One of the most significant complications in patients with liver disease is the development of neurological disturbances, termed hepatic encephalopathy. The pathogenesis of hepatic encephalopathy is incompletely understood, which has resulted in the development of a wide range of experimental models. Congenital portosystemic shunt is one of the most common congenital disorders diagnosed in client owned dogs. Our recent studies have demonstrated that the pathophysiology of canine hepatic encephalopathy is very similar to human hepatic encephalopathy, which provides strong support for the use of dogs with a congenital portosystemic shunt as a naturally occurring model of human hepatic encephalopathy. Specifically, we have demonstrated an important role for ammonia and inflammation in the development of hepatic encephalopathy in dogs with a congenital portosystemic shunt. Despite the apparent importance of inflammation in driving hepatic encephalopathy in dogs, it is unclear whether inflammation resolves following the successful treatment of liver disease. We hypothesized that haematological and biochemical evidence of inflammation, as gauged by neutrophil, lymphocyte and monocyte concentrations together with C-reactive protein concentrations, would decrease following successful treatment of congenital portosystemic shunts in dogs. One hundred and forty dogs with a congenital portosystemic shunt were enrolled into the study. We found that the proportion of dogs with a monocyte concentration above the reference range was significantly greater in dogs with hepatic encephalopathy at time of initial diagnosis. Importantly, neutrophil and monocyte concentrations significantly decreased following surgical congenital portosystemic shunt attenuation. We also found a significant decrease in C-reactive protein concentrations following surgical attenuation of congenital portosystemic shunts. Our study demonstrates that haematological and biochemical indices of inflammation reduce following successful treatment of the underlying liver disorder.

Prostaglandin F₂α modulates atrial chronotropic hyporesponsiveness to cholinergic stimulation in endotoxemic rats

Endotoxemia induces various physiological adaptive responses such as tachycardia. There is evidence to show that inflammatory tachycardia might be linked to a direct action of prostanoids on the cardiac pacemaker cells. Recent reports have indicated that systemic inflammation may uncouple of cardiac pacemaker from cholinergic neural control in experimental animals; however, the exact mechanism of this phenomenon is uncertain. This study was aimed to explore the hypothesis that prostanoids modulate atrial chronotropic hyporesponsiveness to cholinergic stimulation in endotoxemic rats. Male albino rats were given intraperitoneal injection of either saline or lipopolysaccharide (LPS, 1 mg/kg). 3 h after saline or LPS injection, the atria were isolated and chronotropic responsiveness to cholinergic stimulation was evaluated in an organ bath. The expression of atrial cyclooxygenases (COX)-1, COX-2 and COX-3 mRNA was assessed by quantitative real-time RT-PCR and cytosocalcium-dependent phospholipase A₂ (cPLA₂) activity was measured in the atria. The expression of atrial COX-2 mRNA and cPLA₂ activity increased significantly in endotoxemic atria (P<0.05). Incubation with prostaglandin F₂α (PGF₂α, 100 pM) could significantly decrease chronotropic response to cholinergic stimulation in vitro. Likewise, LPS injection could induce a significant hyporesponsiveness to cholinergic stimulation, and incubation of isolated atria with either indomethacin (5 µM) or AL-8810 (a PGF₂α antagonist, 10 µM) could reverse it (P<0.01, P<0.05, respectively), while SQ29548 (a thromboxane A₂ antagonist, 10 nM) was failed (P>0.05). Our data showed that PGF₂α may contribute to the atrial chronotropic hyporesponsiveness to cholinergic stimulation in endotoxemic rats.

Anatomical localization of commensal bacteria in immune cell homeostasis and disease

The mammalian gastrointestinal (GI) tract is colonized by trillions of beneficial commensal bacteria that are essential for promoting normal intestinal physiology. While the majority of commensal bacteria are found in the intestinal lumen, many species have also adapted to colonize different anatomical locations in the intestine, including the surface of intestinal epithelial cells (IECs) and the interior of gut-associated lymphoid tissues. These distinct tissue localization patterns permit unique interactions with the mammalian immune system and collectively influence intestinal immune cell homeostasis. Conversely, dysregulated localization of commensal bacteria can lead to inappropriate activation of the immune system and is associated with numerous chronic infectious, inflammatory, and metabolic diseases. Therefore, regulatory mechanisms that control proper anatomical containment of commensal bacteria are essential to maintain tissue homeostasis and limit pathology. In this review, we propose that commensal bacteria associated with the mammalian GI tract can be anatomically defined as (i) luminal, (ii) epithelial-associated, or (iii) lymphoid tissue-resident, and we discuss the role and regulation of these microbial populations in health and disease.

Urinary metabolite profiling offers potential for differentiation of liver-kidney yin deficiency and dampness-heat internal smoldering syndromes in posthepatitis B cirrhosis patients

Zheng is the basic theory and essence of traditional Chinese medicine (TCM) in diagnosing diseases. However, there are no biological evidences to support TCM Zheng differentiation. In this study we elucidated the biological alteration of cirrhosis with TCM "Liver-Kidney Yin Deficiency (YX)" or "Dampness-Heat Internal Smoldering (SR)" Zheng and the potential of urine metabonomics in TCM Zheng differentiation. Differential metabolites contributing to the intergroup variation between healthy controls and liver cirrhosis patients were investigated, respectively, and mainly participated in energy metabolism, gut microbiota metabolism, oxidative stress, and bile acid metabolism. Three metabolites, aconitate, citrate, and 2-pentendioate, altered significantly in YX Zheng only, representing the abnormal energy metabolism. Contrarily, hippurate and 4-pyridinecarboxylate altered significantly in SR Zheng only, representing the abnormalities of gut microbiota metabolism. Moreover, there were significant differences between two TCM Zhengs in three metabolites, glycoursodeoxycholate, cortolone-3-glucuronide, and L-aspartyl-4-phosphate, among all differential metabolites. Metabonomic profiling, as a powerful approach, provides support to the understanding of biological mechanisms of TCM Zheng stratification. The altered urinary metabolites constitute a panel of reliable biological evidence for TCM Zheng differentiation in patients with posthepatitis B cirrhosis and may be used for the potential biomarkers of TCM Zheng stratification.

Commensal microbiota is hepatoprotective and prevents liver fibrosis in mice

Translocation of bacteria and their products across the intestinal barrier is common in patients with liver disease, and there is evidence that experimental liver fibrosis depends on bacterial translocation. The purpose of our study was to investigate liver fibrosis in conventional and germ-free (GF) C57BL/6 mice. Chronic liver injury was induced by administration of thioacetamide (TAA) in the drinking water for 21 wk or by repeated intraperitoneal injections of carbon tetrachloride (CCl4). Increased liver fibrosis was observed in GF mice compared with conventional mice. Hepatocytes showed more toxin-induced oxidative stress and cell death. This was accompanied by increased activation of hepatic stellate cells, but hepatic mediators of inflammation were not significantly different. Similarly, a genetic model using Myd88/Trif-deficient mice, which lack downstream innate immunity signaling, had more severe fibrosis than wild-type mice. Isolated Myd88/Trif-deficient hepatocytes were more susceptible to toxin-induced cell death in culture. In conclusion, the commensal microbiota prevents fibrosis upon chronic liver injury in mice. This is the first study describing a beneficial role of the commensal microbiota in maintaining liver homeostasis and preventing liver fibrosis.

Portal vein thrombosis in cirrhosis

Portal vein thrombosis (PVT) is being increasingly recognized in patients with advanced cirrhosis and in those undergoing liver transplantation. Reduced flow in the portal vein is probably responsible for clotting in the spleno-porto-mesenteric venous system. There is also increasing evidence that hypercoagulability occurs in advanced liver disease and contributes to the risk of PVT. Ultrasound based studies have reported a prevalence of PVT in 10-25% of cirrhotic patients without hepatocellular carcinoma. Partial thrombosis of the portal vein is more common and may not have pathophysiological consequences. However, there is high risk of progression of partial PVT to complete PVT that may cause exacerbation of portal hypertension and progression of liver insufficiency. It is thus, essential to accurately diagnose and stage PVT in patients waiting for transplantation and consider anticoagulation therapy. Therapy with low molecular weight heparin and vitamin K antagonists has been shown to achieve complete and partial recanalization in 33-45% and 15-35% of cases respectively. There are however, no guidelines to help determine the dose and therapeutic efficacy of anticoagulation in patients with cirrhosis. Anticoagulation therapy related bleeding is the most feared complication but it appears that the risk of variceal bleeding is more likely to be dependent on portal pressure rather than solely related to coagulation status. TIPS has also been reported to restore patency of the portal vein. Patients with complete PVT currently do not form an absolute contraindication for liver transplantation. Thrombectomy or thromboendovenectomy is possible in more than 75% of patients followed by anatomical end-to-end portal anastomosis. When patency of the portal vein and/or superior mesenteric vein is not achieved, only non-anatomical techniques (reno-portal anastomosis or cavo-portal hemitransposition) can be performed. These techniques, which do not fully reverse portal hypertension, are associated with higher morbidity and mortality risks in the short term.

Cirrhosis-associated immune dysfunction: distinctive features and clinical relevance

The term cirrhosis-associated immune dysfunction refers to the main syndromic abnormalities of immune function, immunodeficiency and systemic inflammation that are present in cirrhosis. The course of advanced cirrhosis, regardless of its aetiology, is complicated by cirrhosis-associated immune dysfunction and this constitutes the pathophysiological hallmark of an increased susceptibility to bacterial infection, distinctive of the disease. Cirrhosis impairs the homeostatic role of the liver in the systemic immune response. Damage to the reticulo-endothelial system compromises the immune surveillance function of the organ and the reduced hepatic synthesis of proteins, involved in innate immunity and pattern recognition, hinders the bactericidal ability of phagocytic cells. Systemic inflammation, in form of activated circulating immune cells and increased serum levels of pro-inflammatory cytokines, is the result of persistent episodic activation of circulating immune cells from damage-associated molecular patterns, released from necrotic liver cells and, as cirrhosis progresses, from pathogen-associated molecular patterns, released from the leaky gut. Cirrhosis-associated immune dysfunction phenotypes switch from predominantly "pro-inflammatory" to predominantly "immunodeficient" in patients with stable ascitic cirrhosis and in patients with severely decompensated cirrhosis and extra-hepatic organ failure (e.g. acute-on-chronic liver failure), respectively. These cirrhosis-associated immune dysfunction phenotypes represent the extremes of a spectrum of reversible dynamic events that take place during the course of cirrhosis. Systemic inflammation can affect the functions of tissue somatic cells and modify the clinical manifestation of cirrhosis. The best characterized example is the contribution of systemic inflammation to the haemodynamic derangement of cirrhosis, which correlates negatively with prognosis.

Characterisation of temporal microglia and astrocyte immune responses in bile duct-ligated rat models of cirrhosis

BACKGROUND & AIMS

Microglia and astrocyte related pro-inflammatory responses are thought to underpin cerebral sequelae of acute liver failure. Conversely, despite background pro-inflammatory responses in cirrhosis, overt brain swelling and coma associated with acute-on-chronic liver failure, is infrequent unless precipitated (e.g. sepsis). Moreover in other chronic neurodegenerative disorders and sepsis, the brain is protected from recurrent microbial insults by compensatory microglial-associated immune responses. To characterise longitudinal cerebral immune responses in a bile duct-ligated (BDL) rat model of cirrhosis.

METHOD

Rats underwent BDL or sham operation before sacrifice at either 1-day, 1, 2 and 4 weeks post-surgery. We analysed consciousness, brain water, biochemistry and immunohistochemistry to assess activation of microglia (ED-1, OX6 and Iba-1), astrocytes (Glial fibrillary acidic protein - GFAP), cellular stress (Heat shock protein - Hsp 25) and pro-inflammatory mediator expression (inducible nitric oxide synthase (iNOS), interleukin-1beta (IL-1β) and tumour growth factor-beta (TGF-β)).

RESULTS

BDL significantly increased ammonia and bilirubin (P < 0.01 respectively). The classical microglial markers OX6, ED1 and Iba-1 and pro-inflammatory IL-1β and iNOS were not significantly increased. However, the alternative microglial marker and regulatory cytokine TGF-β was elevated from day 1 to 4 weeks post-BDL. GFAP expression was significantly increased in corpus callosum in all groups. In BDL rats, Hsp 25 was also increased in the corpus callosum, peaking at 2 weeks.

CONCLUSION

BDL triggers early alternative, but not classical, microglial activation. There was a correlation between astrocyte activation and cellular stress. These findings indicate early cerebral immune responses, which may be associated with immune tolerance to further challenge.

The role of the gut microbiome in the development and progression of liver cirrhosis and hepatocellular carcinoma

Liver cirrhosis and hepatocellular carcinoma (HCC) represent the endstage of most chronic liver diseases and are a major global health burden. It has been consistently shown that both liver cirrhosis and HCC are triggered by inflammatory processes, but the molecular mechanisms linking chronic hepatitis with cirrhosis and HCC are only poorly understood. Recent studies suggested that the intestinal microflora as a main source of portal-vein LPS might play a critical role in this process. Here we summarize the available literature on the role of the gut microbiome in hepatofibrogenesis and -carcinogenesis. Such knowledge might help to develop novel, innovative strategies for the prevention and therapy of liver disease.

Genetic variation in TNFA predicts protection from severe bacterial infections in patients with end-stage liver disease awaiting liver transplantation

BACKGROUND & AIMS

Augmented susceptibility to infections increases mortality in patients with end-stage liver disease (ESLD). We sought to determine the contribution of selected genetic variants involved in inflammatory signalling downstream of the Toll-like receptor 4 (TLR4) to severe bacterial infections (SBIs) in patients with ESLD.

METHODS

We retrospectively assessed incidence of SBIs in 336 adult ESLD patients enlisted for orthotopic liver transplantation (OLT) and genotyped them for TLR4 c.+1196C/T, CD14 c.-159C/T, TNFA c.-238G/A, TNFA c.-863C/A, IL1B c.-31C/T and IL1RN variable number of tandem repeats allelic variants. Principal findings were validated in an independent cohort of 332 ESLD patients.

RESULTS

Thirty-four percent of patients from the identification cohort and 40% of patients from the validation cohort presented with SBI while enlisted for OLT. The presence of the variant allele TNFA c.-238A (rs361525) was associated with lower serum levels of TNF-α, and with significantly decreased risk of SBI in both cohorts. Multivariate analysis showed that the relative protection from SBI associated with this allele almost completely negated the increased susceptibility to SBI owed to advanced ESLD. Although not predictive of overall mortality, the presence of the TNFA c.-238A allele was associated with a complete prevention of SBI-related pre-transplant deaths.

CONCLUSIONS

Our results suggest that genetic variability in inflammatory signalling is associated with the development of SBI in patients with ESLD. Specifically, we identified the importance of the TNFA c.-238A allele as a strong predictor of protection from SBI, and as a genetic marker associated with significantly improved pre-transplant survival in patients with SBI.

Adrenal dysfunction in portal hypertensive rats with acute hemorrhage

Nitric oxide (NO) participates in shock and poorer portal hypotensive effect to vasoconstrictors in portal hypertension with hemorrhage, the so-called splanchnic hyposensitivity. Relative adrenal insufficiency accompanies hemorrhagic shock and is found in liver disease, the ‘hepatoadrenal syndrome’, but the relevant interactions remain unsettled. Portal hypertensive rats were induced by partial portal vein ligation (PVL). Experiments were performed on the 14^th day post PVL: (I) ACTH stimulation test for rats without or with hemorrhage; (II) Glypressin response (mean arterial pressure, MAP; portal pressure, PP) in rats (a) without hemorrhage or with hemorrhage, injected with (b) distilled water (DW), (c) dexamethasone 3 mg/kg; (III) To survey the dose-dependent effects of glucocorticoid without being confounded by endogenous adrenal hormone, glypressin response was surveyed in PVL rats with adrenalectomy: (a) without hemorrhage or with hemorrhage, injected with (b) DW; (c) dexamethasone 3 mg/kg; (d) dexamethasone 5 mg/kg. Plasma tumor necrosis factor-α (TNF-α) concentrations and abdominal aorta (AA), superior mesenteric artery (SMA) NO synthases (NOS) mRNA expressions were determined. The results showed that ACTH induced corticosterone release similarly in PVL rats with or without hemorrhage. In bleeding PVL rats, dexamethasone (1) down-regulated AA NOS and enhanced glypressin-induced MAP elevation; (2) did not influence glypressin-induced PP reduction; (3) reduced TNF-α. In bleeding PVL and adrenalectomized rats, high-dose dexamethasone (1) down-regulated AA/SMA NOS; (2) enhanced glypressin-induced MAP elevation and PP reduction; (3) reduced TNF-α. In conclusion, bleeding portal hypertensive rats failed to enhance corticosterone release, suggesting a relative adrenal insufficiency. High-dose dexamethasone reversed systemic hypotension and splanchnic hyporesponsiveness to glypressin in adrenalectomized PVL rats accompanied by TNF-α and NOS down-regulation, suggesting the importance of adequate adrenocorticoid supplement in portal hypertension with hemorrhage and adrenal dysfunction.

Increased toll-like receptor 4 in cerebral endothelial cells contributes to the astrocyte swelling and brain edema in acute hepatic encephalopathy

Astrocyte swelling and the subsequent increase in intracranial pressure and brain herniation are major clinical consequences in patients with acute hepatic encephalopathy. We recently reported that conditioned media from brain endothelial cells (ECs) exposed to ammonia, a mixture of cytokines (CKs) or lipopolysaccharide (LPS), when added to astrocytes caused cell swelling. In this study, we investigated the possibility that ammonia and inflammatory agents activate the toll-like receptor 4 (TLR4) in ECs, resulting in the release of factors that ultimately cause astrocyte swelling. We found a significant increase in TLR4 protein expression when ECs were exposed to ammonia, CKs or LPS alone, while exposure of ECs to a combination of these agents potentiate such effects. In addition, astrocytes exposed to conditioned media from TLR4-silenced ECs that were treated with ammonia, CKs or LPS, resulted in a significant reduction in astrocyte swelling. TLR4 protein up-regulation was also detected in rat brain ECs after treatment with the liver toxin thioacetamide, and that thioacetamide-treated TLR4 knock-out mice exhibited a reduction in brain edema. These studies strongly suggest that ECs significantly contribute to the astrocyte swelling/brain edema in acute hepatic encephalopathy, likely as a consequence of increased TLR4 protein expression by blood-borne noxious agents.

Thymoquinone alleviates thioacetamide-induced hepatic fibrosis and inflammation by activating LKB1-AMPK signaling pathway in mice

The current study was conducted to investigate the anti-fibrotic effect and its possible underlying mechanisms of thymoquinone (TQ) against hepatic fibrosis in vivo. TQ is the major active compound derived from the medicinal Nigella sativa. Liver fibrosis was induced in male Kunming mice by intraperitoneal injections of thioacetamide (TAA, 200 mg/kg). Mice were treated concurrently with TAA alone or TAA plus TQ (20 mg/kg or 40 mg/kg) given daily by oral gavage. Our data demonstrated that TQ treatment obviously reversed liver tissue damage compared with TAA alone group, characterized by less inflammatory infiltration and accumulation of extracellular matrix (ECM) proteins. TQ significantly attenuated TAA-induced liver fibrosis, accompanied by reduced protein and mRNA expression of α-smooth muscle actin (α-SMA), collagen-І and tissue inhibitor of metalloproteinase-1 (TIMP-1). TQ downregulated the expression of toll-like receptor 4 (TLR4) and remarkably decreased proinflammatory cytokine levels as well. TQ also significantly inhibited phosphatidylinositol 3-kinase (PI3K) phosphorylation. Furthermore, TQ enhanced the phosphorylation adenosine monophosphate-activated protein kinase (AMPK) and liver kinase B (LKB)-1. In conclusion, TQ may reduce ECM accumulation, and it may be at least regulated by phosphorylation of AMPK signaling pathways, suggesting that TQ may be a potential candidate for the therapy of hepatic fibrosis.

Sophocarpine attenuates liver fibrosis by inhibiting the TLR4 signaling pathway in rats

AIM: To explore the effect of sophocarpine on experimental liver fibrosis and the potential mechanism involved.

METHODS: Sophocarpine was injected intraperitoneally in two distinct rat hepatic fibrosis models induced either by dimethylnitrosamine or bile duct ligation. Masson’s trichrome staining, Sirius red staining and hepatic hydroxyproline level were used for collagen determination. Primary hepatic stellate cells (HSCs) were isolated and treated with different concentrations of sophocarpine. Real-time reverse transcription-polymerase chain reaction was used to detect the mRNA levels of fibrotic markers and cytokines. The expression of pathway proteins was measured by Western blot. The Cell Counting Kit-8 test was used to detect the proliferation rate of activated HSCs treated with a gradient concentration of sophocarpine.

RESULTS: Sophocarpine decreased serum levels of aminotransferases and total bilirubin in rats under chronic insult. Moreover, administration of sophocarpine suppressed extracellular matrix deposition and prevented the development of hepatic fibrosis. Furthermore, sophocarpine inhibited the expression of α-smooth muscle actin (SMA), interleukin (IL)-6, transforming growth factor-β1 (TGF-β1), Toll-like receptor 4 (TLR4), and extracellular-related kinase (ERK) in rats. Sophocarpine also down-regulated the mRNA expression of α-SMA, collagen I, collagen III, TGF-β1, IL-6, tumor necrosis factor-α and monocyte chemoattractant protein-1, and decreased protein levels of TLR4, p-ERK, p-JNK, p-P38 and p-IKK in vitro after Lipopolysaccharide induction. In addition, sophocarpine inhibited the proliferation of HSCs accompanied by a decrease in the expression of Cyclin D1. The protein level of proliferating cell nuclear antigen was decreased in activated HSCs following a gradient concentration of sophocarpine.

CONCLUSION: Sophocarpine can alleviate liver fibrosis mainly by inhibiting the TLR4 pathway. Sophocarpine may be a potential chemotherapeutic agent for chronic liver diseases.