Debbie L. Shawcross

Anti-tumor necrosis factor-alpha monoclonal antibody therapy in severe alcoholic hepatitis

BACKGROUND/AIMS Severe alcoholic hepatitis (AH) is associated with high mortality. Tumor necrosis factor-alpha (TNFalpha) has been demonstrated to play an important role in its pathophysiology. METHODS Twelve patients with biopsy-confirmed AH and a Maddrey discriminant factor >32 were treated with a single infusion of the anti-TNF monoclonal antibody Infliximab at a dose of 5mg/kg body weight. Serial measurements were made for various cytokines using specific enzyme-linked immunoassays (ELISA). In four patients, liver biopsy samples were available pretreatment and on day+28 of therapy. RESULTS Ten of the 12 patients are alive at a median of 15 (12-20) months. Two patients died within 30 days from septicemia. Serum bilirubin levels, Maddrey score, neutrophil count and C-reactive protein fell significantly within the first month. There was an early, though not significant, decrease in plasma levels of proinflammatory cytokines (interleukins (IL)-1beta, IL-6, IL-8, interferon-gamma), whereas plasma levels of TNFalpha remained near the sensitivity limit of the assay throughout the treatment course. While TNFalpha mRNA expression in the liver did not change, expression of IL-8, a cytokine regulated mainly by TNFalpha, was almost absent on day+28. CONCLUSIONS Our data suggest that randomized controlled trials of anti-TNF antibody in severe AH are warranted.

Review article: the design of clinical trials in hepatic encephalopathy - an International Society for Hepatic Encephalopathy and Nitrogen Metabolism (ISHEN) consensus statement

Aliment Pharmacol Ther 2011; 33: 739–747

Meld score and serum sodium in the prediction of survival of patients with cirrhosis awaiting liver transplantation

Background/Aims: Serum sodium predicts prognosis in cirrhosis and may improve the prognostic accuracy of the model for end-stage liver disease (MELD) score, but the available information is limited. The aim of the present study was to assess the prognostic value of serum sodium in the prediction of survival at 3 and 12 months after listing in patients with cirrhosis awaiting liver transplantation, and to compare its predictive value with that of the MELD score. Patients and methods: 308 consecutive patients with cirrhosis listed for transplantation during a 5-year period were included in the study. The end-point was survival at 3 and 12 months before transplantation. Variables obtained at the time of listing were analysed for prognostic value using multivariable analysis. Accuracy of prognostic variables was analysed by receiver operating characteristic (ROC) curves. Results: The MELD score and serum sodium concentration were the only independent predictors of survival at 3 and 12 months after listing. Low serum sodium was associated with an increased risk of death in all subpopulations of patients with cirrhosis categorised according to the major complication developed before listing. The area under the ROC curves for serum sodium and MELD score was not significantly different both at 3 months (0.83 vs 0.79, respectively) and at 12 months (0.70 vs 0.77, respectively). The addition of serum sodium did not significantly improve the accuracy of the MELD score in the prediction of survival at 3 and 12 months. Conclusion: In patients with cirrhosis awaiting liver transplantation, serum sodium and MELD were found to be independent predictors of survival. Larger studies are needed to determine whether the addition of serum sodium to MELD can improve its prognostic accuracy.

Endotoxemia produces coma and brain swelling in bile duct ligated rats

This study explores the hypothesis that the inflammatory response induced by administration of lipopolysaccharide (LPS) exacerbates brain edema in cirrhotic rats; and if so whether this is associated with altered brain metabolism of ammonia or anatomical disturbance of the blood‐brain barrier. Adult Sprague‐Dawley rats 4 weeks after bile duct ligation (BDL)/Sham‐operation, or naïve rats fed a hyperammonemic diet (HD), were injected with LPS (0.5 mg/kg, intraperitoneally) or saline, and killed 3 hours later. LPS administration increased brain water in HD, BDL, and sham‐operated groups significantly (P < 0.05), but this was associated with progression to pre‐coma stages only in BDL rats. LPS induced cytotoxic brain swelling and maintained anatomical integrity of the blood‐brain barrier. Plasma/brain ammonia levels were higher in HD and BDL rats than in sham‐operated controls and did not change with LPS administration. Brain glutamine/myoinositol ratio was increased in the HD group but reduced in the BDL animals. There was a background pro‐inflammatory cytokine response in the brains of cirrhotic rats, and plasma/brain tumor necrosis factor alpha (TNF‐α) and IL‐6 significantly increased in LPS‐treated animals. Plasma nitrite/nitrate levels increased significantly in LPS groups compared with non‐LPS controls; however, frontal cortex nitrotyrosine levels only increased in the BDL + LPS rats (P < 0.005 versus BDL controls). Conclusion: Injection of LPS into cirrhotic rats induces pre‐coma and exacerbates cytotoxic edema because of the synergistic effect of hyperammonemia and the induced inflammatory response. Although the exact mechanism of how hyperammonemia and LPS facilitate cytotoxic edema and pre‐coma in cirrhosis is not clear, our data support an important role for the nitrosation of brain proteins. (HEPATOLOGY 2007.)

Infection and systemic inflammation, not ammonia, are associated with Grade 3/4 hepatic encephalopathy, but not mortality in cirrhosis

BACKGROUND & AIMS Patients with cirrhosis are prone to infection which is a frequent precipitant of hepatic encephalopathy (HE). Clinical studies have examined the importance of inflammation and infection in modulating the manifestation of symptoms of HE in acute liver failure and patients with cirrhosis and minimal/low grade HE. It would be logical to presume that this relationship persists in patients who develop severe HE in cirrhosis although this has not been examined to date. METHODS We report the findings of a prospective audit of 100 consecutive patients with cirrhosis admitted between Jan 2000 and March 2008 to a liver Intensive Care Unit (ICU) where HE was the primary indication for admission (59% Grade 3; 41% Grade 4). Haematological and microbiological data were collected at ICU admission, and organ scores and outcomes were recorded. RESULTS 46% of patients had positive cultures taken within ± 48h from admission to ICU [25% blood] and a further 22% were culture negative but had evidence of systemic inflammation (SIRS). SIRS score (p=0.03) and SOFA score (p=0.006) were significantly higher in those patients with Grade 4 HE, who were also less likely to survive (p<0.001). HE grade/coma score did not correlate with ammonia, biochemistry or MELD score. Fifty-two percent of patients survived their ICU stay while the remainder developed progressive multiorgan failure and died; 38% survived to discharge, and 16% were transplanted. CONCLUSIONS These data support an association between infection/SIRS and not ammonia, in patients with cirrhosis that develop severe HE. The presence or absence of infection/SIRS did not determine survival.

Ammonia and the neutrophil in the pathogenesis of hepatic encephalopathy in cirrhosis

Hepatic encephalopathy (HE) constitutes a neuropsychiatric syndrome which remains a major clinical problem in patients with cirrhosis. In the severest form of HE, cirrhotic patients may develop varying degrees of confusion and coma. Ammonia has been regarded as the key precipitating factor in HE, and astrocytes have been the most commonly affected cells neuropathologically. Although the evidence base supporting a pivotal role of ammonia is robust, in everyday clinical practice a consistent correlation between the concentration of ammonia in the blood and the manifest symptoms of HE is not observed. More recently the synergistic role of inflammation and infection in modulating the cerebral effects of ammonia has been shown to be important. Furthermore, it has been recognized that infection impairs brain function both in the presence and absence of liver disease. Thus it could be postulated that in the presence of ammonia, the brain is sensitized to a systemic inflammatory stimulus and is able to elicit an inflammatory response involving both proinflammatory and neurotransmitter pathways. Ammonia is not only directly toxic to astrocytes but induces neutrophil dysfunction with the release of reactive oxygen species, which contribute to oxidative stress and systemic inflammation. This may further exacerbate the cerebral effects of ammonia and potentially reduce the capacity of the neutrophil to fight microbial attack, thus inducing a vicious circle. This evidence supports the neutrophil in addition to ammonia as being culpable in the pathogenesis of HE, making the neutrophil a target for future anti‐inflammatory therapeutic strategies in addition to ammonia lowering therapies. (HEPATOLOGY 2010.)

Dispelling myths in the treatment of hepatic encephalopathy

CONTEXT Guidelines for the treatment of hepatic encephalopathy suggest ammonia reduction as the main focus, based on strategies to reduce ammonias generation and absorption in the colon by using lactulose and a reduced protein diet. STARTING POINT Two studies provide compelling and provocative data questioning the relevance of these interventions. Bodils Als-Nielsen and colleagues, in a systematic review of randomised trials, found insufficient evidence about whether non-absorbable disaccharides are beneficial (BMJ 2004; 328: 1046-50). In a small randomised study, Juan Cordoba and colleagues showed that diets with normal protein content can be administered safely during episodic hepatic encephalopathy due to cirrhosis and that protein restriction does not have any beneficial effect during such episodes (J Hepatol 2004; 41: 38-43). WHERE NEXT Two approaches to new therapies for hepatic encephalopathy are needed. First, it is important to focus on the interorgan metabolism of ammonia. The small intestine and kidneys might be important producers of ammonia, and muscle is an important organ that can remove ammonia. Novel therapies targeting these organs reduce ammonia. Second, research is needed to explore factors other than ammonia that might be important in hepatic encephalopathy, including the synergistic role of inflammation. The lack of conclusive data about the efficacy of any treatment supports the view that placebo-controlled trials of newer agents are needed and ethical. The emphasis should shift to aggressive management of the precipitating event.

High-volume plasma exchange in patients with acute liver failure: An open randomised controlled trial.

BACKGROUND & AIMS Acute liver failure (ALF) often results in cardiovascular instability, renal failure, brain oedema and death either due to irreversible shock, cerebral herniation or development of multiple organ failure. High-volume plasma exchange (HVP), defined as exchange of 8-12 or 15% of ideal body weight with fresh frozen plasma in case series improves systemic, cerebral and splanchnic parameters. METHODS In this prospective, randomised, controlled, multicentre trial we randomly assigned 182 patients with ALF to receive either standard medical therapy (SMT; 90 patients) or SMT plus HVP for three days (92 patients). The baseline characteristics of the groups were similar. The primary endpoint was liver transplantation-free survival during hospital stay. Secondary-endpoints included survival after liver transplantation with or without HVP with intention-to-treat analysis. A proof-of-principle study evaluating the effect of HVP on the immune cell function was also undertaken. RESULTS For the entire patient population, overall hospital survival was 58.7% for patients treated with HVP vs. 47.8% for the control group (hazard ratio (HR), with stratification for liver transplantation: 0.56; 95% confidence interval (CI), 0.36-0.86; p=0.0083). HVP prior to transplantation did not improve survival compared with patients who received SMT alone (CI 0.37 to 3.98; p=0.75). The incidence of severe adverse events was similar in the two groups. Systemic inflammatory response syndrome (SIRS) and sequential organ failure assessment (SOFA) scores fell in the treated group compared to control group, over the study period (p<0.001). CONCLUSIONS Treatment with HVP improves outcome in patients with ALF by increasing liver transplant-free survival. This is attributable to attenuation of innate immune activation and amelioration of multi-organ dysfunction.

Ammonia impairs neutrophil phagocytic function in liver disease

Hyperammonemia is a feature of liver failure, which is associated with increased risk of infection. The aims of the present study were to determine in vitro, in rats fed an ammoniagenic diet and in patients with cirrhosis, whether induction of hyperammonemia results in neutrophil dysfunction. As hyperammonemia produces cell swelling, we explored the role of the osmoregulating, p38 mitogen‐activated protein kinase (p38MAPK) pathway in mediating this neutrophil dysfunction. Neutrophils were isolated from blood of healthy volunteers and incubated with either 75 μM ammonia or phosphate‐buffered saline. Both groups were studied under hyponatremic conditions and/or with the addition of p38MAPK modulators. Neutrophil phagocytosis was measured in naive rats and rats fed an ammoniagenic diet and in patients with stable cirrhosis given placebo (n = 8) or an amino acid solution inducing hyperammonemia (n = 8). Cell volume and phagocytosis was analyzed by fluorescent‐activated cell sorting using fluorescein isothiocyanate–labeled E. coli. p38MAPK phosphorylation was measured by western blotting. In healthy neutrophils incubated with ammonia and in rats fed an ammoniagenic diet, neutrophils showed evidence of swelling, impaired phagocytosis, and increased spontaneous oxidative burst compared to controls. Phagocytosis was significantly impaired in patients with induced hyperammonemia compared to placebo. The effects of hyperammonemia and hyponatremia were synergistic. The p38MAPK intracellular signaling pathways were activated in healthy neutrophils exposed to ammonia in association with increased burst activity. Neutrophil phagocytic dysfunction was abrogated by the addition of a p38MAPK agonist. Conclusion: Ammonia produces neutrophil swelling and impairs neutrophil phagocytosis. The p38MAPK intracellular signaling pathway has been shown to be important in mediating the ammonia‐induced neutrophil dysfunction. (HEPATOLOGY 2008.)

The molecular pathogenesis of hepatic encephalopathy

Hepatic encephalopathy (HE) incorporates a spectrum of neuropsychiatric abnormalities seen in patients with liver dysfunction with a potential for full reversibility. Distinct syndromes are identified in acute liver failure and cirrhosis. Rapid deterioration in consciousness level and increased intracranial pressure that may result in brain herniation and death are a feature of acute liver failure whereas manifestations of HE in cirrhosis include psychomotor dysfunction, impaired memory, increased reaction time, sensory abnormalities, poor concentration and in severe forms, coma. For over a 100 years ammonia has been considered central to its pathogenesis. In the brain, the astrocyte is the main site for ammonia detoxification, during the conversion of glutamate to glutamine. An increased ammonia level raises the amount of glutamine within astrocytes, causing an osmotic imbalance resulting in cell swelling and ultimately brain oedema. The present review focuses upon the molecular mechanisms involved in the pathogenesis of HE. Therapy of HE is directed primarily at reducing ammonia generation and increasing its detoxification.