Circulating acute phase cytokines and cytokine inhibitors in fulminant hepatic failure: associations with mortality and haemodynamics

The importance of immune dysfunction in determining outcome in acute liver failure

Acute liver failure (ALF) shares striking similarities with septic shock with regard to the features of systemic inflammation, progression to multiple organ dysfunction and functional immunoparesis. While the existence of opposing systemic pro- and anti-inflammatory profiles resulting in organ failure and immune dysfunction are well recognised in septic shock, characterization of these processes in ALF has only recently been described. This review explores the evolution of the systemic inflammation in acute liver failure, its relation to disease progression, exacerbation of liver injury and development of innate immune dysfunction and extra-hepatic organ failure as sequelae. Defects in innate immunity are described in hepatic and extra-hepatic compartments. Clinical studies measuring levels of pro- and anti-inflammatory cytokines and expression of the antigen presentation molecule HLA-DR on monocytes, in combination with ex-vivo experiments, demonstrate that the persistence of a compensatory anti-inflammatory response syndrome, leading to functional monocyte deactivation, is a central event in the evolution of systemic immune dysfunction. Accurate immune profiling in ALF may permit the development of immunomodulatory strategies in order to improve outcome in this condition.

Arterial ammonia and clinical risk factors for encephalopathy and intracranial hypertension in acute liver failure

High circulating ammonia concentrations are common in patients with acute liver failure (ALF) and are associated with hepatic encephalopathy (HE) and intracranial hypertension (ICH). Other risk factors are poorly characterized. We evaluated the relation of the admission arterial ammonia concentration and other clinical variables with the development of HE and ICH. Arterial ammonia was measured on admission to the intensive care unit in 257 patients; 165 had ALF and severe HE, and there were 3 control groups: acute hepatic dysfunction without severe HE (n = 50), chronic liver disease (n = 33), and elective surgery (n = 9). Variables associated with ICH and HE were investigated with regression analysis. Ammonia was higher in ALF patients than controls. An independent risk factor for the development of severe HE and ICH, a level greater than 100 mumol/L predicted the onset of severe HE with 70% accuracy. The model for end-stage liver disease (MELD) score was also independently predictive of HE, and its combination with ammonia increased specificity and accuracy. ICH developed in 55% of ALF patients with a level greater than 200 mumol/L, although this threshold failed to identify most cases. After admission, ammonia levels remained high in those developing ICH and fell in those who did not. Youth, a requirement for vasopressors, and renal replacement therapy were additional independent risk factors.

CONCLUSION

Ammonia is an independent risk factor for the development of both HE and ICH. Additional MELD scoring improved the prediction of HE. Factors other than ammonia also appear important in the pathogenesis of ICH. Ammonia measurements could form part of risk stratification for HE and ICH, identifying patients for ammonia-lowering therapies and invasive monitoring.

Reduced monocyte HLA-DR expression: a novel biomarker of disease severity and outcome in acetaminophen-induced acute liver failure

Acute liver failure (ALF) shares striking similarities with septic shock where a decrease in HLA-DR expression on monocytes is associated with disease severity and predicts outcome. We investigated monocyte HLA-DR expression in ALF in relation to inflammatory mediator levels and clinical outcome. Monocyte HLA-DR expression was determined in 50 patients with acetaminophen-induced ALF (AALF) and 20 non-acetaminophen-induced ALF (NAALF). AALF patients were divided into dead/transplanted (AALF-NS, n = 26) and spontaneous survivors (AALF-S, n = 24). Fifty patients with chronic liver disease (CLD) and 50 healthy volunteers served as controls. Monocyte HLA-DR expression was determined by double-color flow-cytometry with monoclonal antibodies detecting HLA-DR and monocyte specific CD14. Serum levels of interleukin (IL) -4, -6, -10, tumor necrosis factor (TNF)-alpha and interferon (IFN)-gamma were concomitantly measured by ELISA. Compared to healthy volunteers (75%) and CLD (67%) monocyte HLA-DR percentage expression was lower in AALF (15%, P < .001) and NAALF (22 %, P < .001). Compared to AALF-S, AALF-NS had lower monocyte HLA-DR % (11% vs. 36%, P < .001) and higher levels of IL-4, IL-6, IL-10 and TNF-alpha (P < .001). HLA-DR percentage negatively correlated with INR, blood lactate, pH and levels of encephalopathy (r = -0.8 to -0.5, P < .01), IL-10 (r = -0.8, P < .0001), TNF-alpha (r = -0.4, P = .02). HLA-DR percentage level <or=15% has a 96% sensitivity and 100% specificity and 98% accuracy in predicting poor prognosis. In conclusion, the strong relationship of monocyte HLA-DR expression with indices of disease severity, mediators of inflammation and outcome indicates a key role for this molecule as a biomarker of disease severity and prognosis.

Fulminant hepatic failure

The rare but potentially devastating clinical syndrome of fulminant hepatic failure has as its components severe encephalopathy and finally cerebral edema, hemodynamic instability, renal failure, coagulopathy, profound metabolic disturbances and a particular susceptibility to bacterial and fungal infection. Despite advances in medical management, fulminant hepatic failure in its most severe form carries a high mortality rate unless urgent orthotopic liver transplantation is carried out. However, availability of cadaveric donor organs is limited and, due to the rapidly progressive clinical course in many cases, a substantial proportion of patients will die or develop contraindications to transplantation before the procedure can be performed. Consequently, recent interest has centred on living donor transplantation and the possibility of providing temporary liver support, either through auxiliary partial organ transplantation, extracorporeal perfusion or transplantation of hepatocytes, to allow time for either a liver graft to become available or native liver regeneration, on which spontaneous survival ultimately depends, to occur.

Fulminant liver failure in a child with invasive group A streptococcal infection

Liver involvement is mentioned in streptococcal toxic shock syndrome, but never as fulminant liver failure (FLF). We report the case of a 2-year-old child who developed isolated FLF secondary to invasive group A streptococcal infection without shock due to a M1T1-type strain expressing speA, speB and speC toxin genes. On antibiotics, he recovered rapidly without liver transplantation.

CONCLUSION

A streptococcal pyrogenic exotoxin likely constituted the initial insult leading to FLF. This etiology can be included in the differential diagnosis of FLF and would support early introduction of antibiotics.