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

Superimposed coagulopathic conditions in cirrhosis: infection and endogenous heparinoids, renal failure, and endothelial dysfunction

In this article, the authors discuss three pathophysiologic mechanisms that influence the coagulation system in patients who have liver disease. First, bacterial infections may play an important role in the cause of variceal bleeding in patients who have liver cirrhosis, affecting coagulation through multiple pathways. One of the pathways through which this occurs is dependent on endogenous heparinoids, on which the authors focus in this article. Secondly, the authors discuss renal failure, a condition that is frequently encountered in patients who have liver cirrhosis. Finally, they review dysfunction of the endothelial system. The role of markers of endothelial function in cirrhotic patients, such as von Willebrand factor and endothelin-1, is discussed.

Effect of intravenous albumin on endotoxin removal, cytokines, and nitric oxide production in patients with cirrhosis and spontaneous bacterial peritonitis

OBJECTIVE

In patients with cirrhosis and spontaneous bacterial peritonitis (SBP), the use of intravenous albumin has been shown to prevent deterioration of renal function and to decrease the mortality rate, but the mechanisms remain unclear. The purpose of this study was to characterize the mechanisms of action of albumin with the focus on endotoxin and cytokines.

MATERIAL AND METHODS

Thirty patients with SBP were divided into two groups. Group 1 received antibiotics and albumin infusion (20% 50 cc every day for 3 days) and Group 2 received antibiotic treatment only. Twenty-four cirrhotic patients with sterile ascites were enrolled in Group 3 and received albumin infusion (20% 50 cc every day for 3 days). Plasma and ascitic fluid concentrations of endotoxin, nitric oxide products (NOx), tumor necrosis factor (TNF)-alpha, and interleukin (IL)-6 were analyzed before and after treatments, respectively.

RESULTS

Combination therapy of albumin and antibiotics can significantly (p<0.01) reduce plasma levels of TNF-alpha and IL-6, and ascitic fluid levels of endotoxin, TNF-alpha and IL-6 in cirrhotic patients with SBP. Without the addition of albumin to an antibiotic regimen, the plasma and ascitic fluid levels of NOx increased significantly in patients with SBP (p=0.005 and p=0.004, respectively).

CONCLUSIONS

The results confirm that the beneficial effects of albumin are related to the reduction of the levels of TNF-alpha and NOx in both plasma and ascitic fluid. The infusion of albumin continuously for 3 days in addition to antibiotic treatment at the time of SBP detection is recommended as an effective therapy for patients with cirrhosis and SBP.

Uncoupling of sympathetic nervous system and hypothalamic-pituitary-adrenal axis in cirrhosis

BACKGROUND AND AIM

The hypothalamic-autonomic nervous system (HANS) axis and the hypothalamic-pituitary-adrenal (HPA) axis are stimulated in parallel in response to stress factors under healthy conditions. This physiological synergism of the axes aims at optimizing anti-inflammatory actions. Therefore, we investigated whether this synergism is altered in patients with liver cirrhosis.

METHODS

As a typical marker of the HANS axis neuropeptide Y (NPY is a neurotransmitter of the sympathetic nerve terminal) and of the HPA axis, cortisol together with adrenocorticotropic hormone (ACTH) and cortisol-binding globulin (CBG), were measured in samples from control subjects and patients with liver cirrhosis.

RESULTS

Plasma NPY was found to be increased in cirrhotic patients compared to control subjects (P < 0.01). This increase was observed to be independent of the severity of liver disease (Child class). Serum cortisol was decreased in cirrhotics, particularly in patients with Child A cirrhosis. Plasma NPY was positively correlated with serum cortisol in control subjects (r = 0.32, P < 0.05) reflecting the parallel activation of both axes under the normal condition. However, serum cortisol was not correlated with plasma NPY in cirrhotic patients. For the subgroup of Child A patients, even a negative correlation between NPY and cortisol was observed (r = -0.43, P < 0.05). No significant change in serum levels of ACTH and its positive correlation with serum cortisol was observed in cirrhotic patients.

CONCLUSIONS

The present study demonstrates that the two stress axes seem to act in parallel fashion in control subjects but are uncoupled in liver cirrhosis. We discuss how uncoupling of the two anti-inflammatory axes can occur and may contribute to the increased susceptibility for infections and lethal complications in cirrhotic patients.

Cirrhotic cardiomyopathy

Cirrhotic cardiomyopathy is a recently recognized condition in cirrhosis consisting of systolic incompetence under condition of stress, diastolic dysfunction related to altered diastolic relaxation, and electrophysiological abnormalities in the absence of any known cardiac disease. It can be diagnosed by using a combination of electrocardiograph, 2-dimensional echocardiography, and various serum markers such as brain natriuretic factor. The underlying pathogenetic mechanisms include abnormalities in the beta-adrenergic signaling pathway, altered cardiomyocyte membrane fluidity, increased myocardial fibrosis, cardiomyocyte hypertrophy, and ion channel defects. Various compounds for which levels are elevated in cirrhosis such as nitric oxide and carbon monoxide can also exert a negative inotropic effect on the myocardium, whereas excess sodium and volume retention can lead to myocardial hypertrophy. Various toxins can also aggravate the ion channel defects, thereby widening the QRS complex causing prolonged QT intervals. Clinically, systolic incompetence is most evident when cirrhotic patients are placed under stress, whether physical or pharmacological, or when the extent of peripheral arterial vasodilatation demands an increased cardiac output as in the case of bacterial infections. Acute volume overload such as immediately after insertion of a transjugular intrahepatic portosystemic shunt or after liver transplantation can also tip these cirrhotic patients into cardiac failure. Treatment of cirrhotic cardiomyopathy is unsatisfactory. There is some evidence that beta-blockade may help some cirrhotic patients with baseline prolonged QT interval. Long-term aldosterone antagonism may help reduce myocardial hypertrophy. Future studies should include further elucidation of pathogenetic mechanisms so as to develop effective treatment strategies.

Probiotics and liver disease

Modulation of intestinal flora through the use of probiotics is an emerging therapeutic strategy in the management of chronic liver diseases. This article focuses on the pathophysiologic basis for using probiotics in liver disease and reviews the existing literature on the subject. The role of probiotics is examined in the following areas: a) prevention of infection, b) the hyperdynamic circulatory state of cirrhosis, c) hepatic encephalopathy, d) liver function, and e) nonalcoholic fatty liver disease.

Hepatic involvement and portal hypertension predict mortality in chronic granulomatous disease

BACKGROUND & AIMS

Chronic granulomatous disease (CGD) is a rare genetic disorder, predisposing affected individuals to recurrent infectious complications and shortened survival. Liver involvement in CGD includes vascular abnormalities, which may lead to noncirrhotic portal hypertension.

METHODS

To evaluate the impact of noncirrhotic portal hypertension on survival in CGD, all records from 194 patients followed up at the National Institutes of Health with CGD were reviewed. Cox proportional hazards regression was used to determine factors associated with mortality.

RESULTS

Twenty-four patients died, all from infectious complications. By Cox regression, factors associated with mortality were as follows: (1) decreases in platelet count (>9000/microL/y; hazard ratio, 4.7; P = .007), (2) alkaline phosphatase level increases (>0.25/y; hazard ratio, 4.5; P = .01) and (3) history of liver abscess (hazard ratio, 3.1; P = .03). By regression analysis, decreasing platelet count was associated with increasing portal vein diameter, splenomegaly, increased serum immunoglobulin G level, and increasing number of alanine aminotransferase increases; greater number of alkaline phosphatase level increases and abscess were both associated with increasing age and number of infections. Prospective evaluation revealed increased hepatic-venous pressure gradients in 2 patients with progressive thrombocytopenia, suggestive of portal hypertension.

CONCLUSIONS

These data suggest mortality in patients with CGD is associated with the development of noncirrhotic portal hypertension, likely owing to injury to the microvasculature of the liver from repeated systemic and hepatic infections. The slope of decline in platelet count may be a useful measure of progression of portal hypertension over time. Furthermore, the data illustrate the potential independent effect of portal hypertension on clinical outcome outside the setting of cirrhosis.

The endocannabinoid system and liver diseases

Endogenous cannabinoids (EC) are ubiquitous lipid signalling molecules provided by a number of central and peripheral effects, which are mainly mediated by the specific cannabinoid receptors CB(1) and CB(2). Although the expression of these receptors is very low or even absent in the healthy liver, a considerable series of experimental studies and some clinical observations have recognised the EC system as an important player in the pathophysiology of liver diseases. The EC system is highly up-regulated during chronic liver diseases and, to date, it has been implicated in the pathogenesis of non-alcoholic fatty liver disease, progression of fibrosis to cirrhosis and the development of the cardiovascular abnormalities of cirrhosis, such as the hyperdynamic circulatory syndrome and cirrhotic cardiomiopathy. Furthermore, the EC system influences the mechanisms responsible for cell damage and the inflammatory response during acute liver injury, such as that resulting from ischaemia-reperfusion. Thus, molecules targeting the CB(1) and CB(2) receptors may represent potential therapeutic agents for the treatment of liver diseases. At present, the CB(1) antagonists represent the most attractive pharmaceutical tool to resolve fat accumulation in patients with non-alcoholic fatty liver disease and to treat patients with cirrhosis, as they may slow the progression of fibrosis and attenuate the cardiovascular alterations associated with the advanced stage of the disease.

Helicobacter pylori infection in hepatic encephalopathy: Relationship to plasma endotoxins and blood ammonia

BACKGROUND/AIM

Hepatic encephalopathy (HE) is frequently observed in patients with advanced liver disease and manifests a wide variety of neuropsychiatric signs and symptoms. Ammonia toxicity and bacterial endotoxins have been suggested as key determinants of HE onset whereas a role for Helicobacter pylori infection has not been established. We investigated the correlation between H. pylori infection and HE severity (evaluated through functional tests) in 60 outpatients with established liver cirrhosis and 20 non-cirrhotic controls.

METHODS

Fasting arterial blood ammonia, plasma endotoxins, and H. pylori infection status were investigated in all subjects.

RESULTS

H. pylori infection was documented in 35/60 (58%) patients and in 6/20 (30%) controls (P = 0.039). Significant differences were observed between patients with and withoutHE for age, presence of ascites, fasting arterial blood ammonia, plasma endotoxin, and H. pylori infection. Further, a significant increase in fasting arterial blood ammonia and plasma endotoxin was associated with H. pylori infection in cirrhotic patients. Last, medical treatment of H. pylori infection led to a significant decrease in HE severity and fasting arterial blood ammonia levels.

CONCLUSION

In conclusion, we submit that H. pylori infection might, in fact, play a role in increasing the circulating levels of ammonia and endotoxins in cirrhotic patients, thus facilitating the onset of HE.

Endocannabinoids acting at CB1 receptors mediate the cardiac contractile dysfunction in vivo in cirrhotic rats

Advanced liver cirrhosis is associated with hyperdynamic circulation consisting of systemic hypotension, decreased peripheral resistance, and cardiac dysfunction, termed cirrhotic cardiomyopathy. Previous studies have revealed the role of endocannabinoids and vascular CB(1) receptors in the development of generalized hypotension and mesenteric vasodilation in animal models of liver cirrhosis, and CB(1) receptors have also been implicated in the decreased beta-adrenergic responsiveness of isolated heart tissue from cirrhotic rats. Here we document the cardiac contractile dysfunction in vivo in liver cirrhosis and explore the role of the endocannabinoid system in its development. Rats with CCl(4)-induced cirrhosis developed decreased cardiac contractility, as documented through the use of the Millar pressure-volume microcatheter system, low blood pressure, and tachycardia. Bolus intravenous injection of the CB(1) antagonist AM251 (3 mg/kg) acutely increased mean blood pressure, as well as both load-dependent and -independent indexes of systolic function, whereas no such changes were elicited by AM251 in control rats. Furthermore, tissue levels of the endocannabinoid anandamide increased 2.7-fold in the heart of cirrhotic compared with control rats, without any change in 2-arachidonoylglycerol levels, whereas, in the cirrhotic liver, both 2-arachidonoylglycerol (6-fold) and anandamide (3.5-fold) were markedly increased. CB(1)-receptor expression in the heart was unaffected by cirrhosis, as verified by Western blotting. Activation of cardiac CB(1) receptors by endogenous anandamide contributes to the reduced cardiac contractility in liver cirrhosis, and CB(1)-receptor antagonists may be used to improve contractile function in cirrhotic cardiomyopathy and, possibly, in other forms of heart failure.

Studies on endotoxin removal mechanism of adsorbents with amino acid ligands

In this paper, a series of adsorbents with different amino acid ligands for endotoxin removal were prepared and endotoxin adsorption capacities (EAC) in aqueous solution were studied using an affinity column. The results showed that the property and structure of amino acid ligands have great influence on EAC. As the increasing of isoelectric point and polarity of amino acids ligands, EACs of the adsorbents increased. In addition, computer simulation method was employed to a further investigation on the interaction between endotoxins and ligands. Based on the results, some adsorbents were applied to remove endotoxin from endotoxemia rabbit's serum. Similar adsorption results were observed and the removal efficiency of adsorbents with Arg, Ser ligands is up to 78%.

Expression of Toll-like receptor 4 in rat liver during the course of carbon tetrachloride-induced liver injury

BACKGROUND AND AIM

It has recently been reported that Toll-like receptor 4 (TLR4) is involved in cellular responses to lipopolysaccharides (LPS) and early liver injury induced by LPS. The aim of the present study was to investigate the alterations of TLR4 gene expression in liver tissues and Kupffer cells during the course of carbon tetrachloride (CCl(4))-induced chronic liver injury and fibrosis and its role in liver injury.

METHODS

Rats were induced with liver injury and fibrosis by CCl(4) administered subcutaneously twice weekly for up to 8 weeks. The Kupffer cells were isolated by the combined collagenase-pronase perfusion method and incubated with varying doses of LPS. The mRNA expression of TLR4 in liver tissues and Kupffer cells was measured by reverse transcriptase polymerase chain reaction. The levels of tumor necrosis factor (TNF)-alpha in Kupffer cell culture supernatants were determined by enzyme-linked immunosorbent assay. The plasma levels of the endotoxin were determined by chromogenic substrate limulus amebocyte lysate assay. The association of the endotoxin receptor expression with plasma endotoxin levels was assessed.

RESULTS

CCl(4) administration elicited extensive changes in liver morphology, including steatosis, inflammation, necrosis, and fibrosis. Low levels of TLR4 mRNA were detected in normal rat liver tissues, but no expression was detected in the Kupffer cells. The expression of TLR4 mRNA in liver tissues and Kupffer cells was increased 2 weeks after CCl(4) administration, peaked at 4 and 6 weeks, and declined at 8 weeks. Basic TNF-alpha production of Kupffer cells isolated from CCl(4)-treated rats at 4 and 6 weeks was significantly higher than that of normal rats (P < 0.05). Upon LPS stimulation, production of TNF-alpha was markedly increased in Kupffer cells isolated from normal and 2-,4-, and 6-week CCl(4)-treated rats. Moreover, LPS-induced TNF-alpha production was dose-dependent. The plasma levels of the endotoxin were increased during the time of liver injury. There was a correlation between plasma endotoxin levels and TLR4 gene expression in the early and middle stage of liver injury.

CONCLUSION

The gene expression of TLR4 was upregulated during the course of CCl(4)-induced liver injury, which is associated with the degree of liver injury and Kupffer cell activation. The gut-derived endotoxin may be involved in the upregulation of TLR4 expression.

Endotoxemia contributes to the immune paralysis in patients with cirrhosis

BACKGROUND/AIMS

Immune paralysis, defined as decreased HLA-DR expression on monocytes and indicated immune dysfunctions, was found in sepsis, severe acute pancreatitis and acute liver failure. However, the relationship between HLA-DR expression and cirrhosis is unclear.

METHODS

We enrolled 64 patients with liver cirrhosis and 23 healthy volunteers. HLA-DR expressions, functions of monocyte, serum cytokines and endotoxin levels were measured.

RESULTS

Compared to healthy volunteers, HLA-DR expressions were significantly lower in Child-Pugh class C cirrhotic patients (89.28% vs 69.29%, p<0.001). These low-HLA-DR-expressed monocytes were with decreased ability of tumor necrosis factor (TNF)-alpha secretion, decreased expression of inducible nitric oxide synthetase (iNOS) and decreased allo-stimulatory ability but normal phagocytosis ability. The co-stimulatory molecules like CD40 and CD86 were down-regulated as well but not CD80. Furthermore, HLA-DR expression was linearly correlated with the presence of hepatic encephalopathy (r(2)=0.2642; p=0.008) and serum interleukin-10 (IL-10) (r(2)=0.2167; p=0.019) in patients with Child-Pugh class C. Serum endotoxin level was in linear relationship to serum IL-10 level (r(2)=0.1868; p=0.002) and HLA-DR expression (r(2)=0.0924; p=0.036). In addition, endotoxin, mediated by IL-10, could down-regulate the HLA-DR expression.

CONCLUSIONS

Child-Pugh class C cirrhotic patients suffer from down-regulation of HLA-DR expression. Endotoxemia, possibly mediated by IL-10, contributes to this HLA-DR down-regulation.

Pathogenesis of hepatic encephalopathy: the tumour necrosis factor-alpha theory

Hepatic encephalopathy (HE) is a major complication for acute and chronic liver failure. Despite several decades of intensive clinical and basic research, the pathogenesis of HE is still incompletely understood, and the precise mechanisms causing brain dysfunction in liver failure are still not fully established. Several theories concerning the pathogenesis of HE have been previously suggested, including the ammonia theory, which received the most attention. These theories are not mutually exclusive and the validity of none of them has been definitely proved experimentally. In this review article, an attractive theory concerning the pathogenesis of HE, the tumour necrosis factor-alpha (TNF) theory, is presented and comprehensively discussed after accumulation of sufficient data which indicate that the pro-inflammatory cytokine, TNF, is strongly involved in the pathogenesis of HE associated with both acute and chronic liver failure. This theory seems to be superior to all other previous theories in the pathogenesis of HE, and may induce development of other beneficial therapeutical modalities for HE directed towards inhibition of TNF production and/or action, and towards enhancement of its degradation.

Bacterial translocation: overview of mechanisms and clinical impact

Bacterial translocation (BT) is a phenomenon in which live bacteria or its products cross the intestinal barrier. Gut translocation of bacteria has been shown in both animal and human studies. BT and its complications have been shown clearly to occur in animal models, but its existence and importance in humans has been difficult to ascertain. We review the mechanisms of BT and its clinical impact based on the current literature.

QT interval correction in patients with cirrhosis

INTRODUCTION

QT interval prolongation is a common electrophysiological abnormality in patients with cirrhosis. As QT interval varies with the heart rate, many QT correction formulas have been proposed, the Bazett's one being the most criticized because it over-corrects the QT interval and may be misleading. This study focused on the QT-RR relationship in patients with cirrhosis to derive a population-specific QT correction formula.

METHODS

One hundred cirrhotic patients of different etiology and severity and 53 healthy controls comparable for age and sex were enrolled. The QT-RR relationship was analyzed in patients by five regression analysis models to derive the population-specific QT-RR equation. The QTc was calculated and compared with those calculated by four common QT correction formulas (Bazett, Fridericia, Framingham, and Hodges). The correlation coefficient QTc-RR was calculated as a measure of the independence of QTc from the original RR interval.

RESULTS

In patients the QT-RR relationship was best described by the power equation "QT = 453.65 x RR1/3.02" (R2 = 0.41), similar to the Fridericia's formula. Bazett's formula led to the longest QTc (P < 0.0001), which was still significantly influenced by the RR interval (R = -0.39; P < 0.0001), while the estimated equation led to a QTc value not influenced by RR (R = -0.014).

CONCLUSION

Bazett's correction should be avoided in patients with cirrhosis because it still provides a rate-dependent QTc value and might be misleading, particularly when assessing the overall preoperative cardiac risk and the effect of drugs affecting the QT interval. In its place, our formula or that of Fridericia can be confidently employed.

Altered immune function of monocytes in different stages of patients with acute on chronic liver failure

The aim of this study was to investigate the characteristics of the immune function of monocytes in different stages of the patients with acute on chronic liver failure (ACLF). Human leucocyte antigen (HLA)-DR and Toll-like receptor 4 (TLR-4) expression on monocytes in early and late stages of acute on chronic liver failure were detected by flow cytometry. The secretion function of monocytes was measured by cytometric bead array. Compared with healthy controls, the levels of HLA-DR expression on monocytes in patients with chronic hepatitis B, liver cirrhosis and acute on chronic liver failure were gradually decreased, especially in the late stage of acute on chronic liver failure (P < 0.001). TLR-4 expression on monocytes in patients with liver cirrhosis and acute on chronic liver failure were higher than the healthy controls. The concentrations of interleukin (IL)-1beta, tumour necrosis factor (TNF)-alpha and IL-12p70 in early-stage ACLF were significantly higher compared with healthy controls and lower in late-stage ACLF (P < 0.01, 0.05). However, a significantly lower amount of IL-10 was found on monocytes in early-stage ACLF than that of late-stage ACLF and healthy controls (P < 0.01). Monocyte HLA-DR expression in patients who died was significantly lower compared with patients who survived in the early and late stages of ACLF (P < 0.01). The dynamic detection of HLA-DR expression or cytokines secreted from monocytes could contribute to the estimation of the status of the immune function of patients with acute on chronic liver failure.

Effects of lactitol on intestinal microflora and plasma endotoxin in patients with chronic viral hepatitis

OBJECTIVES

To investigate the effects of lactitol on intestinal flora and the levels of plasma endotoxin in patients with chronic viral hepatitis.

METHODS

Sixty patients with chronic viral hepatitis and gut-derived endotoxemia were randomly divided into two groups: lactitol group (n=30) and control group (n=30). Patients in the control group received standard medical treatment for 3 weeks, while patients in the lactitol group received lactitol orally in addition to the standard medical treatment. Fecal flora and plasma endotoxin were measured before and after the treatment.

RESULTS

In the lactitol group, the numbers of Bifidobacterium and Lactobacillus per gram of wet feces were significantly increased (p<0.01) and Clostridium perfringens count was decreased markedly (p<0.001). The levels of plasma endotoxin decreased after the treatment from 72.89 ng/L to 33.33 ng/L in the lactitol group and from 66.00 ng/L to 51.07 ng/L in the control group, but the plasma endotoxin levels in the lactitol group decreased far more than in the control group (p<0.01).

CONCLUSIONS

Lactitol can decrease the levels of plasma endotoxin more effectively than standard medical treatment in patients with chronic viral hepatitis through improving intestinal microflora.

Upregulation of TNF-alpha production signaling pathways in monocytes from patients with advanced cirrhosis: possible role of Akt and IRAK-M

BACKGROUND/AIMS

In cirrhosis, tumor necrosis factor (TNF)-alpha overproduction is involved in both the systemic complications and progression of liver injury. Since monocytes from patients with advanced cirrhosis have an increase in lipopolysaccharide (LPS)-induced TNF-alpha production, we hypothesized that an upregulation of TNF-alpha production pathways and/or alteration of constitutive and inducible suppressor of TNF-alpha hyperproduction (protein kinase B (Akt) and interleukin-1 receptor-associated kinase (IRAK)-M, respectively) should be found in monocytes of these patients. Thus, we investigated ex vivo the signaling pathways of TNF-alpha production before and after LPS incubation in monocytes from noninfected Child-Pugh C patients with advanced cirrhosis and healthy subjects.

METHODS

TNF-alpha production, expressions of intracellular TNF-alpha, toll-like receptor-4 (TLR4), IkappaB-alpha, IRAK-1, IRAK-M, mitogen-activated protein (MAP) kinases and Akt activity were measured in monocytes.

RESULTS

Cirrhotic monocytes without LPS have less TLR4 expression, less IkappaB-alpha protein levels, more TNF-alpha expression, higher MAP kinase activities and decreased Akt activity than control monocytes. In cirrhotic monocytes, LPS-induced TNF-alpha hyperproduction and signaling upregulation were associated with a lack of IRAK-M induction.

CONCLUSIONS

Upregulated signaling pathways of the TNF-alpha production, decreased Akt activity and a lack of IRAK-M induction may be involved in the process of cirrhotic monocyte sensitization to produce TNF-alpha.

Association between portal endotoxemia and Child-Pugh classification in complex pathogens-induced hepatic cirrhosis in rats

AIM: To evaluate the association between the Child-Pugh classification and portal endotoxe-mia during the course of rat liver cirrhosis induced by carbon tetrachloride (CCl₄) plus ethanol and cholesterol.

METHODS: Liver cirrhosis model was induced in 20 Wistar rats using CCl₄ plus ethanol and cholesterol, while 6 rats were treated as controls. At 6 and 10 wk, serum samples were collected from portal vein for the detection of prothrombin time, albumin, bilirubin and endotoxin level, and the ascites and brain wave were also tested. The liver function was evaluated by Child-Pugh scoring system and the relationship between Child-Pugh classification and portal endotoxemia was assessed.

RESULTS: Spearman rank correlation analysis showed that Child-Pugh grading was correlated with albumin level and prothrombin time (r = -0.695, P < 0.05; r = 0.649, P < 0.05), but not with bilirubin level (P > 0.05). The level of endotoxin in portal vein was elevated with prolonging of cirrhosis time, and it was significantly higher at 6 or 10 wk than that in the controls (1983.7 ± 586.4, 2600.7 ± 343.8 mEU/L vs 925.1 ± 527.7 mEU/L, both P < 0.01). Endotoxin level was correlated with cirrhosis time (r = 0.624, P < 0.01) and Child-Pugh classification (r = 0.680, P < 0.01).

CONCLUSION: Portal endotoxemia is significantly correlated with Child-Pugh classification, indicating that intestinal endotoxemia plays an important role during the course of complex pathogens-induced cirrhosis in rats.

Gut flora and bacterial translocation in chronic liver disease

Increasing evidence suggests that derangement of gut flora is of substantial clinical relevance to patients with cirrhosis. Intestinal bacterial overgrowth and increased bacterial translocation of gut flora from the intestinal lumen, in particular, predispose to an increased potential for bacterial infection in this group. Recent studies suggest that, in addition to their role in the pathogenesis of overt infective episodes and the clinical consequences of sepsis, gut flora contributes to the pro-inflammatory state of cirrhosis even in the absence of overt infection. Furthermore, manipulation of gut flora to augment the intestinal content of lactic acid-type bacteria at the expense of other gut flora species with more pathogenic potential may favourably influence liver function in cirrhotic patients. Here we review current concepts of the various inter-relationships between gut flora, bacterial translocation, bacterial infection, pro-inflammatory cytokine production and liver function in this group.

Different effects of a CD14 gene polymorphism on disease outcome in patients with alcoholic liver disease and chronic hepatitis C infection

AIM: Clinical and experimental data suggest that gut-derived endotoxins are an important pathogenic factors for progression of chronic liver disease. Recently, a C-T (-159) polymorphism in the promoter region of the CD14 gene was detected and found to confer increased CD14 expression and to be associated with advanced alcoholic liver damage. Here, we investigated this polymorphism in patients with less advanced alcoholic liver disease (ALD) and chronic hepatitis C virus (HCV) infection.

METHODS: CD14 genotyping was performed by PCR-RFLP analysis in (a) 121 HCV patients, (b) 62 patients with alcohol-associated cirrhosis (Alc-Ci), (c) 118 individuals with heavy alcohol abuse without evidence of advanced liver damage (Alc-w/o Ci), and (d) 247 healthy controls. Furthermore, serum levels of soluble CD14 (sCD14) and transaminases were determined.

RESULTS: The TT genotype was significantly more frequent in Alc-Ci compared to Alc-w/o Ci or controls (40.3% vs 23.7% or 24.0%, respectively). In Alc-w/o Ci, serum levels of transaminases did not differ significantly between patients with different CD14 genotypes. In HCV patients, TT-homozygotes had significantly higher sCD14 levels and sCD14 serum levels were significantly higher in patients with advanced fibrosis or cirrhosis. However, no association was found between CD14 genotypes and histological staging or grading.

CONCLUSION: Considering serum transaminases as surrogate markers for alcoholic liver damage, the CD14 polymorphism seems to exhibit different effects during the course of ALD. Differences in genotype distribution between cirrhotic HCV patients and alcoholics and the known functional impact of this polymorphism on CD14 expression levels further indicate differences in the pathophysiological role of CD14 and CD14-mediated lipopolysaccharides signal transduction with regard to the stage as well as the type of the underlying liver disease.

Effect of Helicobacter pylori infection on gastric mucosal pathologic change and level of nitric oxide and nitric oxide synthase

AIM

To investigate the level of nitric oxide (NO) and nitrous oxide synthase (NOS) enzyme and its effect on gastric mucosal pathologic change in patients infected with Helicobacter pylori (H pylori), and to study the pathogenic mechanism of H pylori.

METHODS

The mucosal tissues of gastric antrum were taken by endoscopy, then their pathology, H pylori and anti-CagA-IgG were determined. Fifty H pylori positive cases and 35 H pylori negative cases were randomly chosen. Serum level of NO and NOS was detected.

RESULTS

One hundred and seven cases (71.33%) were anti-CagA-IgG positive in 150 H pylori positive cases. The positive rate was higher especially in those with pre-neoplastic diseases, such as atrophy, intestinal metaplasia and dysplasia. The level of NO and NOS in positive group was higher than that in negative group, and apparently lower in active gastritis than in pre-neoplastic diseases such as atrophy, intestinal metaplasia and dysplasia.

CONCLUSION

H pylori is closely related with chronic gastric diseases, and type I H pylori may be the real factor for H pylori-related gastric diseases. Infection with H pylori can induce elevation of NOS, which produces NO.

Experimental acute alcohol pancreatitis-related liver damage and endotoxemia: synbiotics but not metronidazole have a protective effect

OBJECTIVE

The aim of this study was to test the effect of gut manipulation by either novel synbiotics or by metronidazole on either endotoxemia or the severity of liver damage in the course of acute pancreatitis from alcohol ingestion.

METHODS

Sprague-Dawley rats were fed for 1 week through an intragastric tube a liquid diet with either: (i) 1 mL t.i.d. of a mixture of synbiotics (Lactobacillus acidophilus, Lactobacillus helveticus and Bifidobacterium in an enriched medium); (ii) 20 mg/kg t.i.d. metronidazole; or (iii) standard diet. Then, acute pancreatitis was induced by caerulein and when the disease was full-blown, rats were fed an alcohol-rich diet. Synbiotic and metronidazole treatment was given for a further 2 weeks. Transaminase and endotoxemia levels were measured before treatment, after 6 h, after 24 h and 2 weeks later, at the time the rats were killed. Liver samples were obtained for histological analysis.

RESULTS

Synbiotics but not metronidazole improved the acute pancreatitis-induced increase in endotoxemia and transaminase levels. The addition of alcohol worsened these variables to a limited extent in the synbiotic-treated group, while metronidazole had a negative effect on liver damage.

CONCLUSIONS

Gut flora pretreatment with synbiotics was able to effectively protect against endotoxin/bacterial translocation, as well as liver damage in the course of acute pancreatitis and concomitant heavy alcohol consumption. The beneficial effect of synbiotics on liver histology seems to be correlated with endotoxemia. Metronidazole did not produce such a beneficial effect; in fact, it further worsened liver damage when alcohol was added to the background of ongoing acute pancreatic inflammation.

Nitric oxide and the hyperdynamic circulation in cirrhosis: is there a role for selective intestinal decontamination?

Abnormal vascular tone is responsible for many of the complications seen in cirrhosis making the identification of the pathophysiology of abnormal dilatation a major focus in hepatology research. The study of abnormal vascular tone is complicated by the multiple vascular beds involved (hepatic, splanchnic, peripheral, renal and pulmonary), the differences in the underlying cause of portal hypertension (hepatic versus pre-hepatic) and the slow evolution of the hyperdynamic state. The autonomic nervous system, circulating vasodilators and abnormalities in vascular smooth muscle cells (receptors, ion channels, signalling systems and contraction) have all been implicated. There is overwhelming evidence for an overproduction of NO (nitric oxide) contributing to the peripheral dilatation in both animal models of, and in humans with, cirrhosis and portal hypertension. This review focuses on the proposal that endotoxaemia, possibly from gut-derived bacterial translocation, causes induction of NOS (NO synthase) leading to increased vascular NO production, which is the primary stimulus for the development of vasodilatation in cirrhosis and its accompanying clinical manifestations. The current controversy lies not in whether NO production is elevated, but in which isoform of NOS is responsible. We review the evidence for endotoxaemia in cirrhosis and the factors contributing to gut-derived bacterial translocation, including intestinal motility and permeability, and finally discuss the possible role of selective intestinal decontamination in the management of circulatory abnormalities in cirrhosis.

Lipopolysaccharides induced increases in Fas ligand expression by Kupffer cells via mechanisms dependent on reactive oxygen species

Fas-Fas ligand (FasL)-dependent pathways exert a suppressive effect on inflammatory responses in immune-privileged organs. FasL expression in hepatic Kupffer cells (KC) has been implicated in hepatic immunoregulation. In this study, modulation of FasL expression of KC by endogenous gut-derived bacterial LPS and the role of reactive oxygen species (ROS) as potential mediators of FasL expression in KC were investigated. LPS stimulation of KC resulted in upstream ROS generation and, subsequently, increased FasL expression and consequent Jurkat cell (Fas-positive) apoptosis. The NADPH oxidase and xanthine oxidase enzymatic pathways appear to be major sources of this upstream ROS generation. Increased FasL expression was blocked by antioxidants and by enzymatic blocking of ROS generation. Exogenous administration of H2O2 stimulated KC FasL expression and subsequent Jurkat cell apoptosis. Intracellular endogenous ROS generation may therefore represent an important signal transduction pathway for FasL expression in KC.

Induction of a 72-kDa heat shock protein and protection against lipopolysaccharide-induced liver injury in cirrhotic rats

BACKGROUND AND AIM

A 70-kDa heat shock protein (stress-inducible HSP70, HSP72) has been reported to be a cytoprotectant in a variety of organs. It has been reported that HSP72 protected non-cirrhotic rats against endotoxemia. However, its cytoprotective effect against endotoxemia in cirrhotic rats has not yet been studied. In this study, we investigated the cytoprotective effect of HSP72 on lipopolysaccharide (LPS)-induced liver injury in carbon tetrachloride (CCl(4))-induced cirrhotic rats.

METHODS

Liver cirrhosis was produced by an 8-week intraperitoneal injection of CCl(4) in male Sprague-Dawley rats. Expression of HSP72 was investigated using western blot analysis. Cirrhotic rats were given an intraperitoneal injection of LPS (10 mg/kg) with or without hyperthermia (42.5 degrees C, 15 min) preconditioning. Liver injury was assessed biochemically (aspartate transaminase, alanine transaminase, bilirubin, lactate dehydrogenase, creatinine) and histologically. The plasma tumor necrosis factor (TNF)-alpha level was determined.

RESULTS

Hyperthermia preconditioning induced a 4-fold increase in HSP72 in the cirrhotic rat liver. Pre-induction of HSP72 prevented LPS-induced liver injury, as evaluated using serum biochemical parameters and histology with reduced TNF-alpha response.

CONCLUSION

These findings suggest that pre-induction of HSP72 may provide therapeutic strategies for Gram-negative sepsis-induced liver injury in liver cirrhosis.

Increased hepatic expression of nitric oxide synthase type II in cirrhotic rats

AIM: To determine the role and effect of nitric oxide synthase type II (NOS II) in cirrhotic rats.

METHODS: Expression of NOS II mRNA was detected by real time RT-PCR. The activity of nitric oxide synthase and serum levels of NO, systemic and portal hemodynamics and degrees of cirrhosis were measured with high sensitive methods. Chinese traditional medicine tetrandrine was used to treat cirrhotic rats and to evaluate the function of NO. Double-blind method was applied during the experiment.

RESULTS: The concentration of NO and the activity of NOS were increased markedly at all stages of cirrhosis, and iNOSmRNA was greatly expressed. Meanwhile the portal-venous-pressure (PVP), and portal-venous-flow (PVF) were significantly increased. NO, NOS and iNOSmRNA were positively correlated to the quantity of hepatic fibrosis. Tetrandrine significantly inhibited NO production and the expression of iNOSmRNA.

CONCLUSION: Increased hepatic expression of NOS II is one of the important causes of hepatic cirrhosis and portal hypertension.

Gut microflora in the pathogenesis of the complications of cirrhosis

The gut flora plays an important role in the pathogenesis of the complications of cirrhosis. Cirrhotic patients are prone to develop bacterial infections, mainly the 'spontaneous' infection of ascites or spontaneous bacterial peritonitis. Other complications of cirrhosis, such as variceal haemorrhage and ascites, occur mostly or solely as a consequence of portal hypertension. Portal pressure increases initially as a consequence of an increased intrahepatic resistance but, once collaterals have formed, high portal pressure is maintained by an increased splanchnic blood inflow secondary to vasodilatation. Splanchnic vasodilatation is the initiating event in the hyperdynamic circulatory state that aggravates the complications of cirrhosis. The gut flora plays a role in both the development of infections and in the hyperdynamic circulatory state of cirrhosis and, although less prominently, it also plays a role in the pathogenesis of hepatic encephalopathy. This chapter presents evidence regarding gut flora and its modification in the pathogenesis and management of these complications of cirrhosis.

A pilot study to investigate the use of oxpentifylline (pentoxifylline) and thalidomide in portal hypertension secondary to alcoholic cirrhosis

BACKGROUND

Tumour necrosis factor-alpha is thought to be important in the pathogenesis of portal hypertension. Oxpentifylline (pentoxifylline) and thalidomide inhibit endotoxin-induced tumour necrosis factor-alpha production in vitro.

AIMS

To assess the toxicity of oxpentifylline (pentoxifylline) and thalidomide in cirrhosis and their effect on the hepatic venous pressure gradient and tumour necrosis factor-alpha production.

METHODS

In an open-label pilot study, 20 abstinent patients with stable alcoholic cirrhosis and oesophageal varices were recruited; 12 patients completed haemodynamic measurements before and after treatment with oxpentifylline (pentoxifylline) 1800 mg (n=6) or thalidomide 200 mg (n=6) daily for 2 weeks. Tumour necrosis factor-alpha production was assessed in ex vivo monocyte cultures stimulated with endotoxin.

RESULTS

Thalidomide reduced the hepatic venous pressure gradient from 19.7 mmHg (9.3-23.5 mmHg) to 12.2 mmHg (4.7-19.5 mmHg) (P=0.03) without reducing the hepatic blood flow or altering systemic haemodynamic parameters. Thalidomide reduced ex vivo tumour necrosis factor-alpha production by approximately 50%. Oxpentifylline (pentoxifylline) had no significant effect on any of the parameters measured. Side-effects led to dose reduction or treatment withdrawal in 40% of patients.

CONCLUSION

Thalidomide, but not oxpentifylline (pentoxifylline), reduces the hepatic venous pressure gradient in stable alcoholic cirrhotics, an effect that may be mediated by the inhibition of tumour necrosis factor-alpha production. The role of tumour necrosis factor-alpha inhibitory drugs in the therapy of portal hypertension should be investigated in a randomized controlled trial.

Bacterial translocation up-regulates GTP-cyclohydrolase I in mesenteric vasculature of cirrhotic rats

In cirrhosis, arterial vasodilation and the associated hemodynamic disturbances are most prominent in the mesenteric circulation, and its severity has been linked to bacterial translocation (BT) and endotoxemia. Synthesis of nitric oxide (NO), the main vasodilator implicated, is dependent on the essential cofactor tetrahydrobiopterin (BH(4)). The key enzyme involved in BH(4) synthesis is GTP-cyclohydrolase I (GTPCH-I), which is stimulated by endotoxin. Therefore, we investigated GTPCH-I activity and BH(4) biosynthesis in the mesenteric vasculature of cirrhotic rats with ascites, as well as their relationship with BT and endotoxemia, serum NO, and mean arterial pressure (MAP). GTPCH-I activity and BH(4) content in mesenteric vasculature was determined by high-performance liquid chromatography. BT was assessed by standard bacteriologic culture of mesenteric lymph nodes (MLNs). Serum endotoxin was measured by a kinetic turbidimetric limulus amebocyte lysate assay, and serum NO metabolite (NOx) concentrations were assessed by chemiluminescence. BT was associated with local lymphatic and systemic appearance of endotoxin and was accompanied by increases in serum NOx levels. GTPCH-I activity and BH(4) content in mesenteric vasculature were both increased in animals with BT and correlated significantly (r = 0.69, P <.01). Both GTPCH-I activity and BH(4) levels significantly correlated with serum endotoxin and NOx levels (r = 0.69 and 0.54, 0.81 and 0.53, P <.05). MAP (a marker of systemic vasodilatation) correlated with endotoxemia (r = 0.58, P <.03) and with GTPCH-I activity (r = 0.69, P <.01). In conclusion, in cirrhotic animals BT appears to lead to endotoxemia, stimulation of GTPCH-I, increased BH(4) synthesis, and further enhancement of vascular NO production that leads to aggravation of vasodilatation.

Treatment of endotoxemia

Although recognition of clinical signs of endotoxemia is not difficult, determining the underlying cause for the development of endotoxemia may be a challenging task. For this reason, importance must be placed on performance of a thorough physical examination, attention to detail, and determination of whether or not surgical intervention is required. In most instances, a definitive diagnosis may require repeated examinations and laboratory work. In the meantime, affected animals require treatment for endotoxemia, with the aim being to reduce the duration of endotoxemia, prevent the interaction of additional endotoxins with cell surface receptors, and reduce the synthesis and release of inflammatory mediators.

Transjugular intrahepatic portosystemic shunt for refractory ascites: an analysis of the literature on efficacy, morbidity, and mortality

OBJECTIVES

Transjugular intrahepatic portosystemic shunt (TIPS) is frequently used to treat patients with refractory ascites, but its role is controversial. We sought to determine from the literature the efficacy, morbidity, and mortality associated with TIPS for refractory ascites.

METHODS

We searched MEDLINE and identified studies published in English from January, 1985, to March, 2003, that evaluated the effect of TIPS in patients with refractory ascites. Outcomes that were analyzed included complete resolution of ascites, reduction in ascites, mortality, encephalopathy, stenosis, and renal function. Data were analyzed on an intention to treat basis.

RESULTS

Of 25 studies identified, 16 were included in the analysis. The pooled estimate for complete response at 6 months was 45% and for any response (complete and partial) was 63%. Pooled 6-month mortality after TIPS was 36%. Risk factors for mortality included renal insufficiency (serum creatinine >1.5 mg/dl), hyperbilirubinemia (total bilirubin >3 mg/dl), advanced age (>60 yr), and poor response to TIPS. The pooled rate of new or worsening encephalopathy after TIPS was 32%. In most cases, encephalopathy was managed medically or by reduction in shunt size; however, refractory cases were associated with 100% mortality in most studies. Studies reporting the effect of TIPS on kidney function showed improvement in creatinine clearance and urinary sodium excretion.

CONCLUSIONS

TIPS is effective in eliminating ascites or substantially reducing ascites in cases refractory to medical therapy. Renal insufficiency, refractory encephalopathy, and hyperbilirubinemia were consistently associated with mortality after TIPS. In individuals with risk factors for mortality, alternative strategies should be recommended.

Spontaneous bacterial peritonitis associated with experimental cirrhosis: Comparative effect of different therapeutic options on endotoxinemia and hemodynamic derangement

OBJECTIVE:  The aim of this investigation was to assess the role of different therapeutic options aimed at modifying the gut microecology in experimental liver cirrhosis in view of the cytokine cascade and splanchnic and systemic hemodynamics.

METHODS:  Cirrhosis was induced in male Sprague‐Dawley rats by carbon tetrachloride (CCL4). After the 6th week of CCL4 administration rats were divided into 5 groups for the remaining 6 weeks: (A) saline b.i.d; (B) lactulose 0.5 g b.i.d.; (C) rifaximine 1 mg b.i.d; (D) 2 mL b.i.d of a probiotic mixture and (E) 1 week of rifaximine followed by 5 weeks of probiotic.

RESULTS:  Rats with cirrhosis and ascites showed a significantly high concentration of either portal, splanchnic and systemic endotoxin, as well as plasma TNF‐α concentration (P < 0.05). Rifaximine alone, rifaximine plus probiotic or probiotic alone significantly decreased the plasma endotoxin concentration at each of the three tested sites, as well as the plasma concentration of TNF‐α (P < 0.01). Total Gram‐negative aerobic bacteria count in the stool markedly decreased together with a significant increase of the enterococcal population in the rifaximine plus probiotic group and, to a lesser extent, in the other treatment groups. Treated rats showed a significantly decreased occurrence of bacterial peritonitis and the rifaximine plus probiotic treatment was the most effective regimen. Each of the treatments significantly reduced the percentage of positive culture of either mesenteric lymph node or portal vein samples, rifaximine plus probiotic being the most effective. As compared with healthy control rats, those with cirrhosis showed a significantly lower mean arterial pressure and systemic vascular resistance, but a higher cardiac index and portal pressure. Spontaneous bacterial peritonitis further worsened the systemic vascular resistance, but this was partly improved by the rifaximine plus probiotic treatment.

CONCLUSION:  These data suggest that the association of a nonabsorbable antibiotic with a probiotic beneficially affects the abnormal systemic vasodilatory response in the course of severe liver cirrhosis, probably through the effects on endotoxin and indirect inhibition of TNF−α release.

TNF-alpha and growth hormone resistance in patients with chronic liver disease

Liver cirrhosis is characterized by a severe impairment of the growth hormone/insulin-like growth factor-1 (GH-IGF-1) axis, that is, acquired GH resistance. The condition of the GH-IGF-1 axis in the phase of chronic liver disease (CLD) preceding cirrhosis, however, remains uncertain. The origin of GH resistance during CLD is multifactorial, and to date, the liver functional mass is considered to play a major role. Although proinflammatory cytokines, tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and IL-1beta, were found to be elevated in patients with CLD and were shown to induce a state of GH resistance in other disease models, their involvement in the pathogenesis of GH resistance during CLD has never been investigated. We characterized the GH-IGF-1 axis by analyzing the individual components of the axis (GH, IGF-1, IGF-binding protein-3 [IGFBP-3], acid-labile subunit [ALS]) and the corresponding ratios (GH/IGF-1, GH/IGFBP-3, and GH/ALS) and verified the links with circulating proinflammatory cytokines (TNF-alpha, IL-1beta, and IL-6), in 34 patients with CLD and 12 healthy controls. Evolution of CLD from chronic hepatitis (CH, n = 17) to cirrhosis (CIR, n = 17) was associated with a progressive increase of GH resistance indices (e.g., GH/IGF-1 ratio: controls 0.5 +/- 0.9, CH 15.9 +/- 31.2, p < 0.01 vs. controls; CIR 188.4 +/- 282.7 mU/nmol, p < 0.001 vs. CH and controls), indicating its onset also in the early stages of CLD. The progressive increase in GH resistance indices matched the increase of circulatory TNF-alpha (e.g., TNF-alpha vs. GH/IGF-1, r = 0.54, p < 0.001). A similar trend was found for IL-6 without reaching statistical significance (r = 0.23, p = 0.13). We found undetectable levels of IL-1beta in our sample of patients and controls. We conclude that proinflammatory cytokines play an important role in the pathogenesis of GH resistance in CLD, but TNF-alpha is a major factor. In addition, GH resistance is present in CLD from the early stages. These results could begin new therapeutic lines of attack in the management of CLD.

Peripheral blood mononuclear cell expression of toll-like receptors and relation to cytokine levels in cirrhosis

Activation of macrophages by endotoxin is assumed responsible for increased circulating tumor necrosis factor alpha (TNF-alpha) and soluble TNF receptor (sTNFR) levels in cirrhosis. Relevant to this is expression of Toll-like receptor (TLR) 4 and TLR2, which is critically involved in production of TNF-alpha in response to endotoxin and Gram-positive microbial stimuli, respectively. The first studies on this in cirrhosis are reported here. In 36 cirrhotic patients and 32 controls, we measured (1) circulating endotoxin, TNF-alpha, and sTNFR levels; (2) peripheral blood mononuclear cell (PBMC) expression of TLR4 and TLR2, and (3) in vitro TNF-alpha production by PBMCs stimulated with endotoxin or Staphylococcus aureus enterotoxin B (SEB). PBMC expression of TLR2, circulating TNF-alpha levels, and in vitro TNF-alpha production were reassessed after supplementation with a synbiotic regimen known to increase intestinal levels of Gram-positive bacteria. Endotoxin, TNF-alpha, and sTNFR levels were significantly increased in cirrhosis. Endotoxin levels did not correlate significantly with other parameters. PBMC expression of TLR2 but not TLR4 was significantly up-regulated in cirrhosis and correlated significantly with serum TNF-alpha and sTNFR levels. In vitro TNF-alpha production by PBMCs stimulated by SEB was significantly blunted. Supplementation with the synbiotic regimen resulted in significant up-regulation of PBMC expression of TLR2. Serum TNF-alpha levels were further increased and in vitro TNF-alpha production further reduced in most patients. In conclusion, up-regulation of PBMC expression of TLR2 but not TLR4 occurs in cirrhosis, which implies, contrary to previous assumptions, an important stimulatory role for Gram-positive microbial components but not endotoxin. TLR2 likely contributes to increased circulating TNF-alpha and sTNFR levels in cirrhosis.

Increased lipopolysaccharide binding protein in cirrhotic patients with marked immune and hemodynamic derangement

Intestinal bacterial overgrowth and translocation, both common in cirrhosis with ascites, may lead to the activation of monocytes and lymphocytes, increased levels of proinflammatory cytokines, and enhanced synthesis of nitric oxide present in cirrhosis. Bacterial endotoxin promotes the synthesis of lipopolysaccharide (LPS)-binding protein (LBP), and forms a LPS-LBP complex that binds to CD14. This study was designed to evaluate LBP levels and their correlation to the immune response and the hemodynamic status in cirrhotic patients. Plasma LBP, endotoxin, soluble CD14 (sCD14), cytokines, renin, nitrites, and systemic vascular resistance were determined before and 4 weeks after norfloxacin or placebo in 102 cirrhotic patients and 30 controls. LBP was elevated in 42% of ascitic cirrhotic patients (15.7 +/- 0.7 versus 6.06 +/- 0.5 microg/mL, P <.01). In 60% of high LBP patients, endotoxin was within normal range. Among ascitic patients, those with high LBP showed greater (P <.05) levels of sCD14, tumor necrosis factor alpha (TNF-alpha), interleukin 6 (IL-6), nitrites + nitrates (NOx)/creatinine, and renin, and lower vascular resistance. In the cirrhotic patients with high LBP, norfloxacin normalized (P <.01) LBP (from 16.6 +/- 0.5 to 5.82 +/- 0.8 microg/mL) and sCD14; reduced the level of cytokines, NOx/creatinine, and renin; and increased vascular resistance; but lacked effect in patients with normal LBP. Portal pressure was unchanged after norfloxacin in another group of 18 cirrhotic patients with high and 19 with normal LBP. In conclusion, the subset of ascitic cirrhotic patients with marked immune and hemodynamic derangement is identified by increased LBP levels. Amelioration of these abnormalities by norfloxacin suggests the involvement of enteric bacteria or their products in the triggering of the process.

Plasma endotoxin level of healthy donors

The plasma level of endotoxin was determined in 116 healthy blood donors. After a routine physical and laboratory investigations the endotoxin level was determined with Limulus amebocyte lysate assay (LAL-test) by the chromogenic kinetic method of Bio-Whittaker Co. (USA). Its sensitivity was 0.005-50 EU/ml. The plasma level of endotoxin in most of the healthy donors was less than 1 EU/ml (in the range of 0.01-1.0 EU/ml), but always measurable. The average +/- S.D. was 0.128 +/- 0.215 EU/ml. Because of the high standard deviation and high range of values, the data were distributed into two groups with the means of 0.05 +/- 0.022 EU/ml and 0.294 +/- 0.186 EU/ml. The difference between the groups was significant (p < 0.001). In conclusion, endotoxin can be measured in plasma of healthy individuals.

Endotoxin and its binding proteins in chronic liver disease: the effect of transjugular intrahepatic portosystemic shunting

BACKGROUND

Gut-derived endotoxin is insufficiently cleared by the diseased liver, and thus, is elevated in plasma of patients with chronic liver disease (CLD). Endotoxin action might be modified by binding to soluble CD14 (sCD14) and lipopolysaccharide-binding protein (LBP), both of which have not yet been sufficiently studied in CLD.

METHODS

Endotoxin, sCD14 and LBP have been determined in peripheral blood of 72 patients and 39 control subjects, and in portal and hepatic venous blood of 12 patients during transjugular intrahepatic portosystemic shunt (TIPS) implantation.

RESULTS

Peripheral endotoxin (average 3-fold increased compared to controls), LBP, and sCD14 plasma levels were elevated in chronic liver disease irrespective of Child stage m, preserve/absence of cirrhosis or aetiology. LBP, and sCD14. Furthermore, endotoxin levels in the portal vein (38.1 +/- 6.1 pg/ml) were only slightly elevated compared to the hepatic vein (29.2 +/- 4.4 pg/ml), and peripheral endotoxin levels did not increase after TIPS.

CONCLUSIONS

Decreased hepatocellular function rather than hepatic blood shunting might be responsible for endotoxemia. The elevation in LBP and sCD14 levels may be a consequence of endotoxemia.

Differential expression and localization of nitric oxide synthases in cirrhotic livers of bile duct-ligated rats

Increased vascular nitric oxide (NO) production has been implicated in the pathogenesis of the hyperdynamic circulation in liver cirrhosis. This study investigated the expression of three isoforms of NO synthase (NOS) in rat cirrhotic livers. Cirrhosis was induced by chronic bile duct ligation (BDL). NOS enzyme activity was assessed by L-citrulline generation. Competitive RT-PCR was performed to detect the mRNA levels of NOS. In situ hybridization was done to localize NOS mRNA. Protein expression of NOS was evaluated by Western blotting and immunohistochemistry. The L-citrulline assay showed that constitutive NOS (cNOS) enzymatic activity was decreased, while inducible NOS (iNOS) activity was increased in BDL livers. Both endothelial NOS (eNOS) and neuronal NOS (nNOS) mRNA were detected in BDL and sham rats, but with enhanced expression in BDL rats. eNOS protein was redistributed with less expression in sinusoidal endothelial cells, but the total levels in liver were not changed. nNOS was induced in hepatocytes of BDL rats, in contrast to only a weak signal observed around some blood vessels in sham livers. Intense mRNA and protein expression of iNOS was induced in livers of BDL rats and was localized in hepatocytes, with no or a negligible amount in control livers. In conclusion, iNOS was induced in cirrhotic liver with its activity increased. In contrast, cNOS activity was impaired, regardless of unchanged eNOS protein levels and enhanced nNOS expression. These results suggest that all three types of NOS have a role in cirrhosis, but their expression and regulation are different.

Small intestinal bacterial overgrowth in human cirrhosis is associated with systemic endotoxemia

OBJECTIVES

Systemic endotoxemia has been implicated in various pathophysiological sequelae of chronic liver disease. One of its potential causes is increased intestinal absorption of endotoxin. We therefore examined the association of small intestinal bacterial overgrowth with systemic endotoxemia in patients with cirrhosis.

METHODS

Fifty-three consecutive patients with cirrhosis (Child-Pugh group A, 23; group B, 18; group C, 12) were included. Jejunal secretions were cultivated quantitatively and systemic endotoxemia determined by the chromogenic Limulus amoebocyte assay. Patients were followed up for 1 yr.

RESULTS

Small intestinal bacterial overgrowth, defined as > or = 10(5) total colony forming units per milliliter of jejunal secretions, was present in 59% of patients and strongly associated with acid suppressive therapy. The mean plasma endotoxin level was 0.86 +/- 0.48 endotoxin units/ml (range = 0.03-1.44) and was significantly associated with small intestinal bacterial overgrowth (0.99 vs 0.60 endotoxin units/ml, p = 0.03). During the 1-yr follow-up, seven patients were lost to follow up or underwent liver transplantation and 12 patients died. Multivariate Cox regression showed Child-Pugh group to be the only predictor for survival.

CONCLUSIONS

Small intestinal bacterial overgrowth in cirrhotic patients is common and associated with systemic endotoxemia. The clinical relevance of this association remains to be defined.

Lipopolysaccharides in liver injury: molecular mechanisms of Kupffer cell activation

Endogenous gut-derived bacterial lipopolysaccharides have been implicated as important cofactors in the pathogenesis of liver injury. However, the molecular mechanisms by which lipopolysaccharides exert their effect are not entirely clear. Recent studies have pointed to proinflammatory cytokines such as tumor necrosis factor-alpha as mediators of hepatocyte injury. Within the liver, Kupffer cells are major sources of proinflammatory cytokines that are produced in response to lipopolysaccharides. This review will focus on three important molecular components of the pathway by which lipopolysaccharides activate Kupffer cells: CD14, Toll-like receptor 4, and lipopolysaccharide binding protein. Within the liver, lipopolysaccharides bind to lipopolysaccharide binding protein, which then facilitates its transfer to membrane CD14 on the surface of Kupffer cells. Signaling of lipopolysaccharide through CD14 is mediated by the downstream receptor Toll-like receptor 4 and results in activation of Kupffer cells. The role played by these molecules in liver injury will be examined.

Endocannabinoids acting at vascular CB1 receptors mediate the vasodilated state in advanced liver cirrhosis

Advanced cirrhosis is associated with generalized vasodilation of unknown origin, which contributes to mortality. Cirrhotic patients are endotoxemic, and activation of vascular cannabinoid CB1 receptors has been implicated in endotoxin-induced hypotension. Here we show that rats with biliary cirrhosis have low blood pressure, which is elevated by the CB1 receptor antagonist SR141716A. The low blood pressure of rats with CCl4-induced cirrhosis was similarly reversed by SR141716A, which also reduced the elevated mesenteric blood flow and portal pressure. Monocytes from cirrhotic but not control patients or rats elicited SR141716A-sensitive hypotension in normal recipient rats and showed significantly elevated levels of anandamide. Compared with non-cirrhotic controls, in cirrhotic human livers there was a three-fold increase in CB1 receptors on isolated vascular endothelial cells. These results implicate anandamide and vascular CB1 receptors in the vasodilated state in advanced cirrhosis and indicate a novel approach for its management.

Bacterial [correction of baterial] translocation in humans

Bacterial translocation is a phenomenon in which live bacteria cross the intestinal barrier. The definition may be broadened to include transmural passage of bacterial cell wall components such as lipopolysaccharide and peptidoglycan polysaccharide. After translocation, bacteria or their products reach the mesenteric lymph nodes. From there, it is possible that enteric bacteria, their cell wall components, or both may disseminate throughout the body, causing sepsis, shock, multisystem organ dysfunction, or death of the host. Bacterial translocation and its complications have been shown clearly to occur in animal models, but its existence and importance in humans has been difficult to ascertain. The purpose of this review is to evaluate the data from studies in humans on the occurrence of bacterial translocation and, more importantly, to evaluate its role as a cause of death in humans. Studies from trauma and intensive care centers often imply that bacterial translocation is a major contributor to sepsis, shock, and multisystem organ failure in humans. However, the data reviewed herein do not support that view clearly. Carefully designed studies are needed to determine the relevance of bacterial translocation in human disease.

Detrimental effects of nitric oxide inhibition on hepatic encephalopathy in rats with thioacetamide-induced fulminant hepatic failure

Hepatic encephalopathy is a complex neuropsychiatric syndrome seen secondary to acute liver failure, chronic parenchymal liver disease, or portal-systemic anastomosis. Vasodilatation induced by nitric oxide (NO) may be involved in the development of hepatic coma. However, there are no comprehensive data concerning the effects of NO inhibition on the severity of hepatic encephalopathy. Male Sprague-Dawley rats weighing 300-350 g were used. Fulminant hepatic failure was induced by intraperitoneal injection of thioacetamide (TAA, 350 mg kg-1 day-1) for 3 days. Rats were divided into two groups to receive either NG-nitro-L-arginine methyl ester (L-NAME, 20 mg kg-1 day-1 via intragastric gavage) or normal saline (N/S) from 2 days prior to TAA administration for 5 days. Severity of encephalopathy was assessed by counts of motor activity and neurobehaviour test scores. Plasma levels of endotoxin, tumour necrosis factor-alpha and nitrate/nitrite were determined by the chromogenic Limulus assay, enzyme-linked immunosorbent assay and colorimetric assay, respectively. Compared with N/S-treated rats, the mortality rate was significantly higher in rats receiving L-NAME (59% vs. 18%, P < 0.01). Inhibition of NO had detrimental effects on the counts of motor activities (P < 0.05) and neurobehaviour score (P < 0.01). Rats treated with L-NAME had significantly higher plasma levels of endotoxin (26.7 +/- 3.8 pg mL-1) and tumour necrosis factor-alpha (29.4 +/- 6.5 pg mL-1) compared with rats treated with N/S (13.2 +/- 2.7 pg mL-1 and 11.2 +/- 2.6 pg mL-1, respectively, P < 0.01). Plasma levels of endotoxin and tumour necrosis factor-alpha, but not of nitrate/nitrite, were significantly correlated with the severity of hepatic encephalopathy (P < 0.05). Chronic L-NAME administration had detrimental effects on the severity of encephalopathy in TAA-treated rats, suggesting a protective role of NO in the development of fulminant hepatic failure.