Serum levels of tumor necrosis factor-alpha correlate with severity of hepatic encephalopathy due to chronic liver failure

Changing face of hepatic encephalopathy: Role of inflammation and oxidative stress

The face of hepatic encephalopathy (HE) is changing. This review explores how this neurocognitive disorder, which is associated with both acute and chronic liver injury, has grown to become a dynamic syndrome that spans a spectrum of neuropsychological impairment, from normal performance to coma. The central role of ammonia in the pathogenesis of HE remains incontrovertible. However, over the past 10 years, the HE community has begun to characterise the key roles of inflammation, infection, and oxidative/nitrosative stress in modulating the pathophysiological effects of ammonia on the astrocyte. This review explores the current thoughts and evidence base in this area and discusses the potential role of existing and novel therapies that might abrogate the oxidative and nitrosative stresses inflicted on the brain in patients with, or at risk of developing, HE.

Cardiovascular changes in cirrhosis: pathogenesis and clinical implications

Liver cirrhosis is associated with a wide range of cardiovascular abnormalities including hyperdynamic circulation, cirrhotic cardiomyopathy, and pulmonary vascular abnormalities. The pathogenic mechanisms of these cardiovascular changes are multifactorial and include neurohumoral and vascular dysregulations. Accumulating evidence suggests that cirrhosis-related cardiovascular abnormalities play a major role in the pathogenesis of multiple life-threatening complications including hepatorenal syndrome, ascites, spontaneous bacterial peritonitis, gastroesophageal varices, and hepatopulmonary syndrome. Treatment targeting the circulatory dysfunction in these patients may improve the short-term prognosis while awaiting liver transplantation. Careful fluid management in the immediate post-transplant period is extremely important to avoid cardiac-related complications. Liver transplantation results in correction of portal hypertension and reversal of all the pathophysiological mechanisms that lead to the cardiovascular abnormalities, resulting in restoration of a normal circulation. The following is a review of the pathogenesis and clinical implications of the cardiovascular changes in cirrhosis.

Pentoxifylline does not decrease short-term mortality but does reduce complications in patients with advanced cirrhosis

BACKGROUND & AIMS

Pentoxifylline, an inhibitor of tumor necrosis factor-alpha, is given to patients with liver diseases, but its effects in patients with advanced cirrhosis are unknown. We performed a randomized, placebo-controlled, double-blind trial of its effects in patients with cirrhosis.

METHODS

A total of 335 patients with cirrhosis (Child-Pugh class C) were assigned to groups given either pentoxifylline (400 mg, orally, 3 times daily; n = 164) or placebo (n = 171) for 6 months. The primary end point was mortality at 2 months. Secondary end points were mortality at 6 months and development of liver-related complications.

RESULTS

By 2 months, 28 patients in the pentoxifylline group (16.5%) and 31 in the placebo group (18.2%) had died (P = .84). At 6 months, 50 patients in the pentoxifylline group (30.0%) and 54 in the placebo group (31.5%) had died (P = .75). The proportions of patients without complications (eg, bacterial infection, renal insufficiency, hepatic encephalopathy, or gastrointestinal hemorrhage) were higher in the pentoxifylline group than in the placebo group at 2 months (78.6% vs 63.4%; P = .006) and 6 months (66.8% vs 49.7%; P = .002). The probability of survival without complications was higher in the pentoxifylline group than in the placebo group at 2 and 6 months (P = .04). In multivariate analysis, the factors associated with death were age, the Model for End-Stage Liver Disease score, and presence of early-stage carcinoma. Treatment with pentoxifylline was the only factor associated with liver-related complications.

CONCLUSIONS

Although pentoxifylline does not decrease short-term mortality in patients with advanced cirrhosis, it does reduce the risk of complications.

Cannabidiol ameliorates cognitive and motor impairments in bile-duct ligated mice via 5-HT1A receptor activation

BACKGROUND AND PURPOSE

We aimed to demonstrate the involvement of 5-HT(1A) receptors in the therapeutic effect of cannabidiol, a non-psychoactive constituent of Cannabis sativa, in a model of hepatic encephalopathy induced by bile-duct ligation (BDL) in mice.

EXPERIMENTAL APPROACH

Cannabidiol (5 mg x kg(-1); i.p.) was administered over 4 weeks to BDL mice. Cognition and locomotion were evaluated using the eight-arm maze and the open field tests respectively. Hippocampi were analysed by RT-PCR for expression of the genes for tumour necrosis factor-alpha receptor 1, brain-derived neurotrophic factor (BDNF) and 5-HT(1A) receptor. N-(2-(4-(2-methoxy-phenyl)-1-piperazin-1-yl)ethyl)-N-(2-pyridyl) cyclohexanecarboxamide (WAY-100635), a 5-HT(1A) receptor antagonist (0.5 mg x kg(-1)), was co-administered with cannabidiol. Liver function was evaluated by measuring plasma liver enzymes and bilirubin.

KEY RESULTS

Cannabidiol improved cognition and locomotion, which were impaired by BDL, and restored hippocampal expression of the tumour necrosis factor-alpha receptor 1 and the BDNF genes, which increased and decreased, respectively, following BDL. It did not affect reduced 5-HT(1A) expression in BDL mice. All the effects of cannabidiol, except for that on BDNF expression, were blocked by WAY-100635, indicating 5-HT(1A) receptor involvement in cannabidiol's effects. Cannabidiol did not affect the impaired liver function in BDL.

CONCLUSIONS AND IMPLICATIONS

The behavioural outcomes of BDL result from both 5-HT(1A) receptor down-regulation and neuroinflammation. Cannabidiol reverses these effects through a combination of anti-inflammatory activity and activation of this receptor, leading to improvement of the neurological deficits without affecting 5-HT(1A) receptor expression or liver function. BDNF up-regulation by cannabidiol does not seem to account for the cognitive improvement.

Hypercytokinemia-induced metabolic encephalopathy in a multiple myeloma patient on hemodialysis undergoing autologous stem cell transplantation: clinical response after plasma exchange

We report here a 50-years old female with multiple myeloma-associated chronic renal failure who underwent high-dose chemotherapy supported by autologous hematopoietic stem cell transplantation. She developed progressive encephalopathy on day 5 progressing to coma despite hemodialysis and no obvious organ failure. She finally recovered after a single 1-liter plasma exchange. The final diagnosis was metabolic encephalopathy due to hypercytokinemia, particularly high serum TNF levels. We discuss here the pathogenesis and raise an alert for monitoring cytokine levels in patients with renal failure undergoing high-dose chemotherapy.

IL-6 and IL-18 in blood may discriminate cirrhotic patients with and without minimal hepatic encephalopathy

BACKGROUND AND AIMS

Patients with liver cirrhosis may present minimal hepatic encephalopathy (MHE) that can be unveiled using specific neuropsychologic examination. Evaluation of MHE in cirrhotic patients might have prognostic value. The psychometric HE score (PHES) has been recommended as the "gold standard" in the diagnosis of MHE. It has been proposed that critical flicker frequency (CFF) analysis would be useful for easier detection of MHE. It would also be useful to have some peripheral parameter that could reflect the presence of MHE. It has been recently proposed that inflammation-associated alterations and hyperammonemia may cooperate in the induction of hepatic encephalopathy. The aim of the present work was to assess whether there is a correlation between the alterations in parameters reflecting inflammation, hyperammonemia, and the presence of MHE.

METHODS

We have studied in 55 patients with liver cirrhosis and 26 controls the performance in the PHES battery and the CFF, ammonia, and some interleukins (ILs) as inflammatory markers.

RESULTS

IL-6 and IL-18 were significantly higher (2.5-fold and 2.2-fold, respectively) in patients with MHE than in those without MHE. There were significant correlations between IL-6 or IL-18 levels and PHES score and CFF. Moreover, all patients with MHE had IL-6 levels higher than 11 ng/mL, whereas all patients without MHE had IL-6 levels lower than 11 ng/mL.

CONCLUSIONS

Inflammatory alterations related with IL-6 and IL-18 may contribute to MHE. Serum concentration of IL-6 and IL-18 may be useful to discriminate cirrhotic patients with and without MHE.

Decreased heart rate variability in patients with cirrhosis relates to the presence and degree of hepatic encephalopathy

Heart rate variability (HRV) is reduced in several clinical settings associated with either systemic inflammation or neuropsychiatric impairment. The possibility that the changes in HRV observed in patients with neuropsychiatric impairment might relate to the overproduction of inflammatory cytokines does not seem to have been considered in the studies undertaken to date. HRV is decreased in patients with liver cirrhosis but its relationship to the impairment of neuropsychiatric performance, commonly observed in these patients, is unknown. The aim of this study was to investigate the relationship between HRV, hepatic encephalopathy, and production of inflammatory cytokines in patients with cirrhosis. Eighty patients with cirrhosis [53 men, 27 women; mean (+/-1SD) age 54 +/- 10 yr], classified as neuropsychiatrically unimpaired or as having minimal or overt hepatic encephalopathy, and 11 healthy subjects were studied. HRV was assessed by applying Poincaré plot analysis to the R-R interval series on a 5-min ECG. Inflammatory cytokines (TNF-alpha, IL-6, IL-10, and IL-12) were measured in a subgroup of patients. Long-term R-R variability was significantly decreased in the patients with cirrhosis, in parallel with the degree of neuropsychiatric impairment (P < 0.01) and independently of the degree of hepatic dysfunction (P = 0.011). The relative risk of death increased by 7.7% for every 1-ms drop in this variable. Plasma levels of IL-6 significantly correlated with indexes of both HRV and neuropsychiatric performance. The changes observed in HRV and in neuropsychiatric status in patients with cirrhosis are significantly correlated, most likely reflecting a common pathogenic mechanism mediated by inflammatory cytokines.

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.

Increased intestinal macromolecular permeability and urine nitrite excretion associated with liver cirrhosis with ascites

AIM: To determine intestinal permeability, the serum tumor necrosis factor (TNF)-α level and urine nitric oxide (NO) metabolites are altered in liver cirrhosis (LC) with or without ascites.

METHODS: Fifty-three patients with LC and 26 healthy control subjects were enrolled in the study. The intestinal permeability value is expressed as the percentage of polyethylene glycol (PEG) 400 and 3350 retrieval in 8-h urine samples as determined by high performance liquid chromatography. Serum TNF-α concentrations and urine NO metabolites were determined using an enzyme-linked immunosorbent assay (ELISA) and Greiss reaction method, respectively.

RESULTS: The intestinal permeability index was significantly higher in patients with LC with ascites than in healthy control subjects or patients with LC without ascites (0.88 ± 0.12 vs 0.52 ± 0.05 or 0.53 ± 0.03, P < 0.05) and correlated with urine nitrite excretion (r = 0.98). Interestingly, the serum TNF-α concentra-tion was significantly higher in LC without ascites than in control subjects or in LC with ascites (198.9 ± 55.8 pg/mL vs 40.9 ± 12.3 pg/mL or 32.1 ± 13.3 pg/mL, P < 0.05). Urine nitrite excretion was significantly higher in LC with ascites than in the control subjects or in LC without ascites (1170.9 ± 28.7 &mgr;mol/L vs 903.1 ± 55.1 &mgr;mol/L or 956.7 ± 47.7 &mgr;mol/L, P < 0.05).

CONCLUSION: Increased intestinal macromolecular permeability and NO is probably of importance in the pathophysiology and progression of LC with ascites, but the serum TNF-α concentration was not related to LC with ascites.

The levels of ghrelin, leptin, TNF-alpha, and IL-6 in liver cirrhosis and hepatocellular carcinoma due to HBV and HDV infection

Background/Aim. Malnutrition, a common problem in liver cirrhosis and HCC, may readily deteriorate the clinical functions with resultant poor prognosis. Beside the hyper catabolic state frequently encountered in chronic liver disease and HCC, anorexia and reduced food intake also worsen the malnutrition. The recently discovered peptide hormone ghrelin acts as a counterpart of leptin in regulation of food intake and fat utilization. The aim of the present study was to investigate the ghrelin and leptin levels in cirrhosis and HCC due to hepatitis B and D viruses, and the association of ghrelin and leptin with TNF-α, IL-6 and the severity of the disease. Materials and methods. We measured serum ghrelin, leptin, TNF-α, and IL-6 levels using specific immunoassay in 45 patients (23 cirrhosis, 22 HCC) with HBV and/or HDV and in 25 control subjects. Results. In comparison to controls, serum ghrelin, TNF-α, and IL-6 levels were significantly higher in cirrhosis and HCC (P < .05), whereas serum leptin levels were found decreased (P < .05). There was a positive correlation between ghrelin and TNF-α, and a negative correlation between leptin and TNF-α (P < .05). Conclusion. In cirrhosis and HCC due to HBV or HDV, serum ghrelin levels were increased with a corresponding decrease in serum leptin concentrations, acting as a physiological counterpart of ghrelin. The increasing of ghrelin is more prominent in Child C cirrhosis and the level was correlated with TNF-α. The presence of nutritional and metabolic abnormalities, including malnutrition, in cirrhosis and HCC may, at least partly, elucidate high ghrelin and low leptin levels.

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.

Serum levels of soluble Fas, nitric oxide and cytokines in acute decompensated cirrhotic patients

AIM: To evaluate plasma levels of nitrite/nitrate (NOx), soluble Fas (sFas) antigen, tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) in patients with compensated and acute decompensated cirrhosis and to evaluate mediators causing acute decompensation in liver cirrhosis.

METHODS: This prospective study was conducted in the medical intensive care unit of an academic tertiary center. Fifty-five patients with acute decompensation (gastrointestinal hemorrhage, encephalopathy, hydropic decompensation) and twenty-five patients with compensated liver cirrhosis were included. Blood samples were taken for analyses of sFas, Nox, IL-6, TNF-α. Liver enzymes and kidney functions were also tested.

RESULTS: In patients with acute decompensation, plasma sFas levels were higher than in non-decompensated patients (15 305 ± 4646 vs 12 458 ± 4322 pg/mL, P < 0.05). This was also true for the subgroup of patients with alcoholic liver cirrhosis (P < 0.05). The other mediators were not different and none of the parameters predicted survival, except for ALT (alanine-aminotransferase). In patients with portal-hypertension-induced acute hemorrhage, NOx levels were significantly lower than in patients with other forms of decompensation (70.8 ± 48.3 vs 112.9 ± 74.9 pg/mL, P < 0.05). When NOx levels were normalized to creatinine levels, the difference disappeared. IL-6, TNF-α and sFas were not different between bleeders and non-bleeders. In decompensated patients sFas, IL-6 and NOx levels correlated positively with creatinine levels, while IL-6 levels were dependent on Child class.

CONCLUSION: In acute decompensated cirrhotic patients sFas is increased, suggesting a role of apoptosis in this process and patients with acute bleeding have lower NOx levels. However, in this acute complex clinical situation, kidney function seems to have a predominant influence on mediator levels.

Activation of soluble guanylate cyclase by nitric oxide in lymphocytes correlates with minimal hepatic encephalopathy in cirrhotic patients

Patients with liver cirrhosis with normal neurological and mental status examination may present minimal forms of hepatic encephalopathy, showing intellectual function impairment that cannot be detected through general clinical examination but can be unveiled using specific neuropsychological or neurophysiological examination. Evaluation of minimal hepatic encephalopathy (MHE) in cirrhotic patients would have prognostic value. The psychometric hepatic encephalopathy score (PHES) has been recommended as the "gold standard" in the diagnosis of MHE. Altered modulation of cyclic GMP (cGMP) levels in the brain seems to be responsible for the impairment of some types of cognitive function in liver disease. In animal models of liver disease, some of the alterations in modulation of cGMP levels in the brain are reproduced in lymphocytes. The aim of the present work was to assess whether there is a correlation between the alterations in different parameters involved in modulation of cGMP levels and the presence of MHE in patients with liver disease. We studied in 46 patients with liver cirrhosis and 26 controls the performance in the PHES battery of psychometric tests and the critical flicker frequency (CFF), the concentration of cGMP in plasma and lymphocytes, activation of guanylate cyclase by nitric oxide (NO) in lymphocytes, and several parameters likely involved in altered cGMP homeostasis in liver disease such as ammonia, NO metabolites, and atrial natriuretic peptide (ANP). Activation of guanylate cyclase by NO in lymphocytes and cGMP in plasma were higher and CFF lower in patients with MHE than in patients without MHE. Ammonia, ANP, and metabolites of NO were higher in patients than in controls but were no different in patients with or without MHE. Alteration in activation of guanylate cyclase by NO in lymphocytes correlates with PHES performance, CFF, and ammonia levels. This suggests that altered modulation of guanylate cyclase by NO in lymphocytes would reflect a parallel alteration in the brain occurring in patients with MHE that would be involved in their cognitive impairment.

Changes in the liver function tests during the attacks of familial Mediterranean fever

The present study aims to investigate whether or not FMF patients display abnormal liver functions during attack periods. About 41 consecutive FMF patients with attacks were enrolled on this study. Bilirubin levels, liver transaminases, erythrocyte sedimentation rate and C-reactive protein (C-RP) levels were determined within the first 72 h after the onset of attacks. This procedure could be performed on only 28 of these 41 FMF patients, 4 weeks after the attack of the patients' had completely disappeared. As for the disease control group, 44 patients were determined to be eligible for the study. Another 31 healthy individuals were also included. Hyperbilirubinemia was determined in 11 of the 41 patients (26.8%) with FMF. The number of FMF patients with hyperbilirubinemia was significantly higher than in DC and HC (P < 0.001, P = 0.03, respectively). Levels of liver transaminases slightly increased in four patients with FMF during the attack and two of these four patients had also mild hyperbilirubinemia. A significant correlation was found between C-RP levels and total and unconjugated bilirubin levels in FMF patients with attack (r = 0.43, P = 0.01; r = 0.40, P = 0.02, respectively). In conclusion, mild hyperbilirubinemia may occur in one-fourth of the patients with FMF during the attack period.

Inflammatory cytokines induce protein tyrosine nitration in rat astrocytes

Protein tyrosine nitration may be relevant for the pathogenesis of hepatic encephalopathy (HE). Infections, sepsis, and trauma precipitate HE episodes. Recently, serum levels of tumor necrosis factor (TNF)-alpha were shown to correlate with severity of HE in chronic liver failure. Here the effects of inflammatory cytokines on protein tyrosine nitration in cultured rat astrocytes and rat brain in vivo were studied. In cultured rat astrocytes TNF-alpha (50 pg/ml-10 ng/ml) within 6h increased protein tyrosine nitration. TNF-alpha-induced tyrosine nitration was related to an increased formation of reactive oxygen and nitrogen intermediates, which was downstream from a NMDA-receptor-dependent increase of intracellular [Ca(2+)](i) and nNOS-catalyzed NO production. Astroglial tyrosine nitration was also elevated in brains of rats receiving a non-lethal injection of lipopolysaccharide, as indicated by colocalization of nitrotyrosine immunoreactivity with glial fibrillary acidic protein and glutamine synthetase, and by identification of the glutamine synthetase among the tyrosine-nitrated proteins. It is concluded that reactive oxygen and nitrogen intermediates as well as protein tyrosine nitration by inflammatory cytokines may alter astrocyte function in an NMDA-receptor-, Ca(2+)-, and NOS-dependent fashion. This may be relevant for the pathogenesis of HE and other conditions involving cytokine exposure the brain.

Cardiac and vascular changes in cirrhosis: Pathogenic mechanisms

Cardiovascular abnormalities accompany both portal hypertension and cirrhosis. These consist of hyperdynamic circulation, defined as reduced mean arterial pressure and systemic vascular resistance, and increased cardiac output. Despite the baseline increased cardiac output, ventricular inotropic and chronotropic responses to stimuli are blunted, a condition known as cirrhotic cardiomyopathy. Both conditions may play an initiating or aggravating pathogenic role in many of the complications of liver failure or portal hypertension including ascites, variceal bleeding, hepatorenal syndrome and increased postoperative mortality after major surgery or liver transplantation. This review briefly examines the major mechanisms that may underlie these cardiovascular abnormalities, concentrating on nitric oxide, endogenous cannabinoids, central neural activation and adrenergic receptor changes. Future work should address the complex interrelationships between these systems.

Chronic systemic endotoxin exposure: an animal model in experimental hepatic encephalopathy

Plasma levels of gut-derived endotoxins (lipopolysaccharides, LPS) are often elevated in cirrhotics and are thought to contribute to hepatic encephalopathy. Circulating LPS activates macrophages to produce tumor necrosis factor alpha (TNF-alpha) and other potentially cytotoxic proinflammatory mediators. A pathogenic role for endotoxins is supported by studies showing that treatment with Lacto-bacillusor antibiotics, both of which reduce LPS-producing intestinal Gram-negative bacteria, alleviates experimental liver damage. To mimic the "leaky gut" syndrome with endotoxin translocation into the circulation in cirrhotics, a new animal model was developed. Rats were chronically exposed to ethanol and for the four last weeks also infused with endotoxin into the jugular vein from subcutaneously implanted osmotic minipumps. Animals receiving endotoxin had elevated hepatic expression of both pro- and anti-inflammatory cytokines, but compared to ethanol treatment alone hepatic steatosis and inflammatory changes were only marginally increased. This demonstrates marked endotoxin tolerance, probably as a consequence of a counteracting anti-inflammatory cytokine response. The role of gut-derived endotoxin in hepatic encephalopathy has recently received considerable attention. To further delineate the role and actions of endotoxin and its extrahepatic effects, studies applying both acute challenge and chronic infusion seem warranted. The chronic endotoxin model, mimicking the "leaky gut," may best be combined with more robust ways to impair liver function, such as carbon tetrachloride treatment, bile duct ligation, or galactosamine administration.

Different tumor necrosis factor-alpha-associated leptin expression in rats with dimethylnitrosamine and bile duct ligation-induced liver cirrhosis

Although serum leptin concentrations are reported by several studies to increase in patients with liver cirrhosis, the mechanisms underpinning this increase remain unclear. Circulating tumor necrosis factor alpha (TNF-alpha) concentrations are also recognized to increase in liver cirrhosis. Furthermore, TNF-alpha administration to rodents results in increased expression and secretion of leptin from adipose tissue in a manner dependent on type 1 TNF-alpha receptor (TNF-RI). The present study was undertaken to examine adipose leptin expression and to explore potential relationships between leptin expression and TNF-alpha in subjects with liver cirrhosis. Liver cirrhosis was induced in male Sprague-Dawley rats by dimethylnitrosamine (DMN) administration or by common bile duct ligation (BDL). Ad libitum and pair-fed animals constituted controls. Serum leptin and TNF-alpha concentrations were determined by immunoassay. Gene expression was determined by the reverse transcription-polymerase chain reaction, and protein levels were measured by Western blotting. Serum leptin values after adjustment of body fat mass in DMN-treated rats were significantly higher than in pair-fed or ad libitum groups. Leptin mRNA and protein levels in epididymal fat in DMN rats increased by 1.8-fold and 2.3-fold, respectively, as compared with ad libitum controls, and by 4-fold and 6-fold, respectively, as compared with the pair-fed group. Epididymal TNF-alpha and membranous TNF-RI (mTNF-RI) concentrations were both 2.3 times higher in DMN rats than in ad libitum controls but did not differ between ad libitum and pair-fed groups. Adipose leptin protein levels correlated directly with TNF-alpha and mTNF-RI concentrations in combined DMN, ad libitum, and pair-fed rats (r=0.64 and r=0.49, respectively; P<.05). In BDL-treated rats, however, serum and adipose leptin concentrations were identical to those in ad libitum controls despite 2.1-fold and 2.4-fold increase in epididymal TNF-alpha and mTNF-RI, respectively. TNF-alpha administration to fasting control animals increased serum and adipose leptin concentrations significantly. The observed TNF-alpha-associated leptin up-regulation in DMN-induced, but not in BDL-induced, cirrhotic rats is consistent with distinctly different roles for TNF-alpha in rats with nonbiliary, as opposed to biliary, cirrhosis.

Relationship between tumor necrosis factor-alpha and ammonia in patients with hepatic encephalopathy due to chronic liver failure

BACKGROUND

We have recently demonstrated that in humans, circulating levels of tumor necrosis factor-alpha (TNF) correlate positively with severity of hepatic encephalopathy (HE) due to chronic liver failure.AIM. The main aim of this larger population study is to determine the relationship between TNF and ammonia in patients with HE and chronic liver failure due to liver cirrhosis.

METHODS

Circulating levels of TNF and ammonia were measured in 108 patients with liver cirrhosis due to various etiologies in various clinical grades of HE (grades 0-4). TNF concentrations were measured in venous serum using commercially available solid-phase high sensitivity enzyme-linked immunosorbent assay. Ammonia levels were determined in venous plasma by the enzymatic method, using the glutamate dehydrogenase reaction.

RESULTS

The mean+/-SEM values of circulating levels of TNF and ammonia at presentation in patients with grade 0 of HE (n = 30) were 3.89+/-0.2 pg/mL and 49.8+/-2.8 microg/mL respectively, in patients with grade 1 of HE (n = 26) were 8.56+/-0.34 pg/mL and 101.6+/-6.5 microg/mL respectively, in patients with grade 2 of HE (n = 22) were 11.59+/-0.48 pg/mL and 160.3+/-10.7 microg/mL respectively, in patients with grade 3 of HE (n = 20) were 19.98+/-0.94 pg/mL and 228.8+/-16.1 microg/mL respectively, and in patients with grade 4 of HE (n = 10) were 51.53+/-8.59 pg/mL and 284.2+/-20.3 microg/mL respectively. A significant positive correlation was found between circulating levels of TNF and those of ammonia (r = 0.62, P< 0.0001), and also between circulating levels of both substances and severity of HE in these patients (r = 0.95, P<0.0001, and r = 0.9, P<0.0001 respectively). TNF and ammonia were both significant independent predictors of severity of HE (P<0.0001 for both variables).

CONCLUSION

The results of this study demonstrate a significant relationship between TNF and ammonia in patients with chronic liver failure and HE, and so strengthen the suggestion that TNF could be strongly involved in the pathogenesis of HE in these patients. Hence, we suggest a new theory in the pathogenesis of HE, the "TNF theory".

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.