Dysregulation of the unfolded protein response in db/db mice with diet-induced steatohepatitis.

UNLABELLED: In humans with nonalcoholic fatty liver, diabetes is associated with more advanced disease. We have previously shown that diabetic db/db mice are highly susceptible to methionine choline-deficient diet (MCD)-induced hepatic injury. Because activation of the unfolded protein response (UPR) is an important adaptive cellular mechanism in diabetes, obesity, and fatty liver, we hypothesized that dysregulation of the UPR may partially explain how diabetes could promote liver injury. Db/db and db/m mice were fed the MCD or control diet for 4 weeks to characterize differences in UPR activation and downstream injury. Wildtype mice (C57BLKS/J) fed the MCD or control diet were treated with SP600125; a c-Jun N-terminal kinase (JNK) inhibitor and its effect on liver injury and UPR activation was measured. The MCD diet resulted in global up-regulation of the UPR in both diabetic db/db and nondiabetic db/m mice. db/db mice had an inadequate activation of recovery pathways (GADD34, XBP-1(s)) and accentuated activation of injury pathways related to persistent eif2-α phosphorylation (activating transcription factor 4 [ATF-4], C/EBP homologous transcription factor [CHOP], oxireductase endoplasmic reticulum oxidoreductin-1 [ERO-1α], JNK, nuclear factor kappaB [NF-κB]) compared to db/m mice. This led to increased expression of inflammatory mediators such as tumor necrosis factor alpha (TNF-α), ICAM-1, and MCP-1 compared to db/m mice. Interestingly, whereas pharmacologic JNK inhibition did not prevent the development of MCD diet-induced steatohepatitis, it did attenuate UPR and downstream inflammatory signaling. CONCLUSION: MCD-fed db/db mice develop a more proinflammatory milieu than db/m mice associated with an impaired ability to dephosphorylate eif2-α through GADD34, impairing cellular recovery. These data may enhance our understanding of why diabetics with nonalcoholic steatohepatitis are prone to develop more severe liver injury than nondiabetic patients.

Pentoxifylline for the treatment of non-alcoholic steatohepatitis: a randomized controlled trial.

INTRODUCTION: The burden of non-alcoholic steatohepatitis (NASH) is growing and current pharmacologic treatments are limited by side effects and inconsistent efficacy. Pilot studies suggest that pentoxifylline (PTX) can reduce liver injury in patients with NASH. OBJECTIVE: We sought to determine the tolerability of PTX and its effect on aminotransferases and liver histology in patients with NASH. MATERIAL AND METHODS: Thirty patients with biopsy proven NASH were randomized in a 2:1 fashion to receive 1,200 mg PTX or placebo for 12 months. Metabolic parameters, aminotransferases, liver histology and hepatic gene expression changes were compared. RESULTS: At baseline the groups were similar. Adverse events were mild, most frequently headache and abdominal cramps, and did not differ between groups (p = NS). After 12 months, ALT and AST decreased from 92 ± 12 IU/L to 67 ± 13 IU/L and 67 ± 6 IU/L to 47 ± 6 IU/L (p < 0.05), respectively in patients treated with PTX. No significant effect was seen with placebo. Steatosis and cellular ballooning improved in the PTX group (p < 0.05), whereas no histological feature of steatohepatitis improved with placebo. However, between groups comparison of both biochemical and histological features were nonsignificant. CONCLUSION: Pentoxifylline is safe, well tolerated and improves transaminases and histology in patients with NASH when compared to baseline and may be a reasonable therapeutic modality for the treatment of NASH. However PTX failed to reduce transaminases compared to placebo and did not positively affect any of the metabolic markers postulated to contribute to NASH. Although animal data and small pilot studies in humans have suggested that PTX may be effective as a treatment for NASH, translating this therapy to clinical practice may prove challenging.

The role of etiology in the hyperamylasemia of acute liver failure.

OBJECTIVES: Hyperamylasemia (HA) is often reported in patients with acute liver failure (ALF). Direct toxic effects of acetaminophen on the pancreas have been postulated, but the occurrence of HA in other etiologies raises the question of whether multiorgan failure is part of the pathogenesis of HA in this setting. Our main aim was to describe and analyze the incidence, clinical characteristics, and outcomes of HA in ALF of different etiologies. METHODS: Patients enrolled in the Acute Liver Failure Study Group registry with an admission amylase value available were included. For the purpose of this analysis, HA was defined as > or =3x upper limits of normal. Patients were classified as having acetaminophen (APAP)- or non-APAP-induced ALF, and by amylase group: normal (<115), mildly elevated (115-345), or HA (>345). Significant variables identified by univariate analysis were added to a multiple linear regression model. The primary outcome was overall survival. RESULTS: In total, 622 eligible patients were identified in the database, including 287 (46%) with APAP-induced ALF; 76 (12%) patients met the criteria for HA. Among patients with HA, 7 (9%) had documented clinical pancreatitis. The incidence of HA was similar among APAP (13%) and non-APAP (12%) patients. Although HA was associated with renal failure and greater Model for End-stage Liver Disease scores for both groups, HA was not an independent predictor of mortality in multivariate analysis. CONCLUSIONS: Although not an independent predictor of mortality, HA in ALF was present in all etiologies and was associated with diminished overall survival. HA appeared to be related to renal dysfunction in both groups and multiorgan failure in non-APAP ALF.

Impact of preoperative overt hepatic encephalopathy on neurocognitive function after liver transplantation.

In the current Model for End-Stage Liver Disease allocation system, patients are at risk of suffering repeated episodes of hepatic encephalopathy (HE) while waiting for an orthotopic liver transplantation (OLT); the posttransplantation impact of these episodes has not been well explored. We evaluated the cognitive function and quality of life in a group of OLT recipients (n = 25) who had suffered from overt HE prior to their procedure (HE-PreLT group) and compared their performance to that of a similar group of patients (n = 14) without overt HE (No HE-PreLT group) as well as to controls. Patients were selected from a cohort of 280 patients who underwent OLT during this period; the presence of clinical confounders excluded many of the remaining subjects. Demographic and clinical characteristics were balanced among groups. At an average of 18 months after OLT, we administered 2 neuropsychological batteries [Psychometric Hepatic Encephalopathy Score (PHES) test battery and Repeatable Battery for the Assessment of Neuropsychological Status (RBANS)]; a pyschophysiological test (critical flicker frequency); and the SF-36 quality of life score. The HE-PreLT group scored below controls in 5 of 6 cognitive domains tested by RBANS, 3 of 6 PHES subtests, as well as the critical flicker frequency test. The No HE-PreLT group scored below the controls in 1 of the 6 cognitive domains tested by RBANS. The more severe neurocognitive abnormalities seen in the HE-PreLT group did not appear to affect quality of life, as lower values than normative data were only found in 1 of the 8 SF-36 scales. In conclusion, neurocognitive abnormalities were more severe in liver transplant recipients that had suffered from overt HE prior to OLT. Prospective studies of neurocognitive function pre-OLT and post-OLT are needed to fully determine the impact of such abnormalities.

Vasopressin accelerates experimental ammonia-induced brain edema in rats after portacaval anastomosis.

BACKGROUND/AIMS: Cerebral hyperemia is an important contributor to the development of brain edema in fulminant hepatic failure. Rats receiving an ammonia infusion after portacaval anastomosis (PCA) demonstrate a rise in cerebral blood flow (CBF) with brain edema at 180 min. Vasopressin (VP), a systemic vasoconstrictor which in the rat dilates cerebral vessels through V(2) receptors, was used to ascertain the effects of increasing CBF. METHODS: Changes in CBF were measured with Laser Doppler flowmetry (LDF). Absolute CBF was measured with radioactive microspheres to calculate oxygen and ammonia uptake. RESULTS: Compared to the NH(3)+Vehicle group, VP+NH(3) infusion accelerated the rise in CBF (117+/-21 vs. -6+/-12%, P<0.01), and the development of brain edema (81.09+/-0.17 vs. 80.29+/-0.06%, P<0.01). Radioactive microspheres confirmed these results (254+/-44 vs. 106+/-9.5 ml/min/100 g, P<0.01). Oxygen uptake was similar. Ammonia uptake was more than twofold higher in the VP+NH(3) group. A V(1) antagonist negated the higher mean arterial pressure (MAP) that occurs with VP but cerebral hyperemia still occurred. A V(2) antagonist resulted in similar systemic pressures, CBF and brain water compared to the VP+NH(3) group. CONCLUSIONS: In this model, an increase in CBF with VP hastens the development of brain edema while increasing ammonia delivery to the brain.