Hepatocyte expression of TRAIL pathway regulators correlates with histopathological and clinical parameters in chronic HCV infection.

BACKGROUND AND AIMS: Treatment with pegylated interferon-alpha (PEG-IFN) and ribavirin is the backbone of standard therapy of HCV by mechanisms that are not completely understood. Besides a direct antiviral effect, different immunomodulatory and apoptotic effects have been discussed. Tumor necrosis factor-related apoptosis inducing-ligand (TRAIL) is a member of the tumor necrosis factor (TNF) family with immunomodulatory as well as pro- and antiapoptotic effects and is putatively involved in control of HCV infection. Thus, we analyzed the expression of the TRAIL/TRAIL-receptor system, caspase-8 and cFLIP and examined their prognostic and predictive value for HCV infection and antiviral therapy, respectively. METHODS: We immunohistochemically analyzed liver biopsies of 116 therapy-naive HCV patients before treatment with PEG-IFNα and ribavirin in comparison to healthy liver tissue. Expression levels of TRAIL, TRAIL-R1 to TRAIL-R4, caspase-8 and cFLIP were correlated with sustained virologic response (SVR), genotype and staging of chronic hepatitis. RESULTS: Caspase-8, cFLIP, TRAIL-R2 and TRAIL-R4 were strongly upregulated in HCV patients, whereas TRAIL-R3 was downregulated. SVR correlated with high expression of TRAIL and pro-apoptotic TRAIL-R2 on HCV infected hepatocytes. CONCLUSIONS: Our results suggest a pathophysiological role of TRAIL in both, HCV infection and therapy. Further studies need to elaborate possible TRAIL-related targets for clinical applications.

Cytosolic and nuclear caspase-8 have opposite impact on survival after liver resection for hepatocellular carcinoma.

BACKGROUND: An imbalance between proliferation and apoptosis is one of the main features of carcinogenesis. TRAIL (TNF-related apoptosis-inducing ligand) induces apoptosis upon binding to the TRAIL death receptors, TRAIL receptor 1 (TRAIL-R1) and TRAIL-R2, whereas binding to TRAIL-R3 and TRAIL-R4 might promote cell survival and proliferation. The anti-tumor activity of TRAIL-R1 and TRAIL-R2 agonists is currently investigated in clinical trials. To gain further insight into the regulation of apoptosis in hepatocellular carcinoma (HCC), we investigated the TRAIL pathway and the regulators of apoptosis caspase-8, Bcl-xL and Mcl-1 in patients with HCC regarding patient survival. METHODS: We analyzed 157 hepatocellular carcinoma patients who underwent partial liver resection or orthotopic liver transplantation and healthy control liver tissue using immunohistochemistry on tissue microarrays for the expression of TRAIL-R1 to TRAIL-R4, caspase-8, Bcl-xL and Mcl-1. Immunohistochemical data were evaluated for potential associations with clinico-pathological parameters and survival. RESULTS: Whereas TRAIL-R1 was downregulated in HCC in comparison to normal liver tissue, TRAIL-R2 and -R4 were upregulated in HCC, especially in G2 and G3 tumors. TRAIL-R1 downregulation and upregulation of TRAIL-R2 and TRAIL-R4 correlated with tumor dedifferentiation (G2/G3). TRAIL-R3, Bcl-xL and Mcl-1 showed no differential expression in tumor tissue compared to normal tissue. The expression levels of TRAIL receptors did not correlate with patient survival after partial hepatectomy. Interestingly, in tumor tissue, but not in normal hepatocytes, caspase-8 showed a strong nuclear staining. Low cytosolic and high nuclear staining intensity of caspase-8 significantly correlated with impaired survival after partial hepatectomy, which, for cytosolic caspase-8, was independent from tumor grade. CONCLUSIONS: Assessment of TRAIL-receptor expression patterns may have therapeutic implications for the use of TRAIL receptor agonists in HCC therapy. Tumor-specific nuclear localisation of caspase-8 in HCC suggests an apoptosis-independent function of caspase-8 and correlates with patient survival.

Ischemia/Reperfusion injury in liver surgery and transplantation: pathophysiology.

Liver ischemia/reperfusion (IR) injury is caused by a heavily toothed network of interactions of cells of the immune system, cytokine production, and reduced microcirculatory blood flow in the liver. These complex networks are further elaborated by multiple intracellular pathways activated by cytokines, chemokines, and danger-associated molecular patterns. Furthermore, intracellular ionic disturbances and especially mitochondrial disorders play an important role leading to apoptosis and necrosis of hepatocytes in IR injury. Overall, enhanced production of reactive oxygen species, found very early in IR injury, plays an important role in liver tissue damage at several points within these complex networks. Many contributors to IR injury are only incompletely understood so far. This paper tempts to give an overview of the different mechanisms involved in the formation of IR injury. Only by further elucidation of these complex mechanisms IR injury can be understood and possible therapeutic strategies can be improved or be developed.

MR relaxometry of the liver: significant elevation of T1 relaxation time in patients with liver cirrhosis.

OBJECTIVES: To evaluate hepatic relaxation times T1, T2 and T2* in healthy subjects and patients with liver cirrhosis stratified by the Child-Pugh classification (CPC). METHODS: Sixty-one consecutive patients were stratified by CPC (class A026; B020; C015) and compared with age-matched controls (n = 31). Relaxometry measurements were performed at 1.5 T using six saturation recovery times (200-3,000 ms) to determine liver T1, six echo times (TE 14-113 ms) for T2 and eight TE (4.8-38 ms) for T2* assessment. Signal intensities in selected regions of interest in the liver parenchyma were fitted to theoretical models with least squares minimisation algorithms to determine T1, T2 and T2*. RESULTS: The most significant difference was the higher T1 values (852 ± 132 ms) in cirrhotic livers compared with controls (678 ± 45 ms, P < 0.0001). A less significant difference was seen for T2* (23 ± 5 vs. 26 ± 7 ms). Subdifferentiation showed a statistically significant difference between control group and individual CPC classes as well as between class C and classes A or B for T1 relaxation times. CONCLUSION: Measurement of T1 relaxation time can differentiate healthy subjects from patients with liver cirrhosis, and can distinguish between mild/moderate disease (CPC A/B) and advanced disease (CPC C). KEY POINTS: • Significantly elevated magnetic resonance T1 relaxation times are found in liver cirrhosis. • T1 relaxation times can distinguish healthy subjects from patients with liver cirrhosis. • T1 relaxation times can distinguish Child-Pugh classes Aand B from C.

Entecavir as treatment for reactivation of hepatitis B in immunosuppressed patients.

AIM: To study the efficacy and safety of entecavir (ETV) as first-line therapy for hepatitis B virus (HBV) reactivation due to immunosuppression. METHODS: Four patients that were treated with different immunosuppressive regimens for hematological malignancies, who presented with HBV reactivation were treated with ETV. Clinical outcome, biochemical and virological factors, including quantitative hepatitis B surface antigen (HBsAg) were studied. RESULTS: In all patients, ETV induced suppression of HBV, and rapid clinical improvement without side effects. In one patient with an alanine aminotransferase (ALT) flare, tenofovir was added after 3 mo of treatment. Until death from disease progression at 6 mo after treatment initiation, this patient did not clear HBV infection. Retrospectively, it is highly probable that the patient had been non-adherent. In the other three patients, the virological responses were associated with an expeditious decrease in quantitative HBsAg titers with negativity after 2 mo, and all three had HBsAg seroconversion. In one patient, HBV DNA reached a plateau after 3 mo, before becoming undetectable after 1 year, despite early ALT normalization and undetectable quantitative HBsAg. CONCLUSION: ETV seems to be effective and safe treatment for HBV reactivation. Monitoring of quantitative HBsAg might be an additional useful tool to monitor treatment response.

Differential expression of the TRAIL/TRAIL-receptor system in patients with inflammatory bowel disease.

TNF-related apoptosis inducing-ligand (TRAIL) is a potent inducer of apoptosis and plays an important role in immune regulation. To explore the role of TRAIL in inflammatory bowel disease (IBD), we examined the expression of the TRAIL/TRAIL-receptor system in colonic resections from patients with ulcerative colitis and Crohn's disease in comparison to normal colon and appendicitis. TRAIL and TRAIL-receptor (TRAIL-R) expression was assessed in resections of normal colon, colon of IBD patients, and appendicitis by immunohistochemistry. TRAIL was downregulated in enterocytes of patients with IBD, but was upregulated in mononuclear cells in areas of active mucosal inflammation. For TRAIL-R1, we detected a strong downregulation in the surface epithelium in IBD but not in appendicitis. TRAIL-R2 and TRAIL-R4 were strongly downregulated in the surface epithelium in any kind of mucosal inflammation. TRAIL and TRAIL-R1 are downregulated in enterocytes, and TRAIL is upregulated in mononuclear cells only in IBD but not in normal colon or appendicitis. This may point to a pathophysiologic role of the TRAIL system in inflammatory bowel disease.