The extent of liver steatosis in chronic hepatitis C virus infection is mirrored by caspase activity in serum

BH3-only protein expression determines hepatocellular carcinoma response to sorafenib-based treatment

Hepatocellular carcinoma (HCC) represents a global health challenge with limited therapeutic options. Anti-angiogenic immune checkpoint inhibitor-based combination therapy has been introduced for progressed HCC, but improves survival only in a subset of HCC patients. Tyrosine-kinase inhibitors (TKI) such as sorafenib represent an alternative treatment option but have only modest efficacy. Using different HCC cell lines and HCC tissues from various patients reflecting HCC heterogeneity, we investigated whether the sorafenib response could be enhanced by combination with pro-apoptotic agents, such as TNF-related apoptosis-inducing ligand (TRAIL) or the BH3-mimetic ABT-737, which target the death receptor and mitochondrial pathway of apoptosis, respectively. We found that both agents could enhance sorafenib-induced cell death which was, however, dependent on specific BH3-only proteins. TRAIL augmented sorafenib-induced cell death only in NOXA-expressing HCC cells, whereas ABT-737 enhanced the sorafenib response also in NOXA-deficient cells. ABT-737, however, failed to augment sorafenib cytotoxicity in the absence of BIM, even when NOXA was strongly expressed. In the presence of NOXA, BIM-deficient HCC cells could be in turn strongly sensitized for cell death induction by the combination of sorafenib with TRAIL. Accordingly, HCC tissues sensitive to apoptosis induction by sorafenib and TRAIL revealed enhanced NOXA expression compared to HCC tissues resistant to this treatment combination. Thus, our results suggest that BH3-only protein expression determines the treatment response of HCC to different sorafenib-based drug combinations. Individual profiling of BH3-only protein expression might therefore assist patient stratification to certain TKI-based HCC therapies.

In Severe Alcoholic Hepatitis, Serum Keratin-18 Fragments Are Diagnostic, Prognostic, and Theragnostic Biomarkers

INTRODUCTION

Up to 40% of patients with severe alcoholic hepatitis (AH) die within 6 months of presentation, making prompt diagnosis and appropriate treatment essential. We determined the associations between serum keratin-18 (K18) and histological features, prognosis, and differential response to prednisolone in patients with severe AH.

METHODS

Total (K18-M65) and caspase-cleaved K18 (K18-M30) were quantified in pretreatment sera from 824 patients enrolled in the Steroids or Pentoxifylline for Alcoholic Hepatitis trial (87 with suitable histological samples) and disease controls.

RESULTS

K18 fragments were markedly elevated in severe AH and strongly predicted steatohepatitis (alcoholic steatohepatitis) on biopsy (area under receiver operating characteristics: 0.787 and 0.807). Application of published thresholds to predict alcoholic steatohepatitis would have rendered biopsy unnecessary in 84% of all AH cases. K18-M30 and M65 were associated with 90-day mortality, independent of age and Model for End-stage Liver Disease score in untreated patients. The association for K18-M65 was independent of both age and Model for End-stage Liver Disease in prednisolone-treated patients. Modelling of the effect of prednisolone on 90-day mortality as a function of pretreatment serum K18 levels indicated benefit in those with high serum levels of K18-M30. At low pretreatment serum K18 levels, prednisolone was potentially harmful. A threshold of K18-M30 5 kIU/L predicted therapeutic benefit from prednisolone above this level (odds ratio: 0.433, 95% confidence interval: 0.19-0.95, P = 0.0398), but not below (odds ratio: 1.271, 95% confidence interval: 0.88-1.84, P = 0.199). Restricting prednisolone usage to the former group would have reduced exposure by 87%.

DISCUSSION

In a large cohort of patients with severe AH, serum K18 strongly correlated with histological severity, independently associated with 90-day mortality, and predicted response to prednisolone therapy. Quantification of serum K18 levels could assist in clinical decision-making.

Serum cytokeratin-18 and its relation to liver fibrosis and steatosis diagnosed by FibroScan and controlled attenuation parameter in nonalcoholic fatty liver disease and hepatitis C virus patients

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) has emerged as the most common cause of chronic liver disease worldwide. Multiple diagnostic noninvasive methods for NAFLD were studied (both serological and imaging), either single or combined. Attention has been focused on cytokeratin-18 (CK18) as a novel serological marker for the diagnosis of steatosis/fibrosis in NAFLD and hepatitis C virus (HCV) patients.

AIM

The aim of this study was to evaluate serum CK18 in NAFLD and HCV fibrosis/steatosis and also to correlate its performance with the diagnostic accuracy of transient elastography (TE) and controlled attenuation parameter (CAP) in the diagnosis of fibrosis/steatosis in these patients.

PATIENTS AND METHODS

Three equal groups of participants were enrolled (n=135): group I included patients with chronic HCV, group II included NAFLD patients, and group III included control participants. For all groups, TE/CAP and labs including serum CK18 were performed. Liver biopsy was performed for the NAFLD group.

RESULTS

Serum CK18 was significantly higher in the NAFLD group (19.01±3.49 ng/ml) versus the HCV group (8.95±1.06 ng/ml) and the control group (4.83±1.6 ng/ml) (P<0.001). The CK18 levels in biopsy stages (steatosis, ballooning, inflammation, and fibrosis) and FibroScan/CAP degrees showed that CK18 increased significantly with steatosis and fibrosis stages (biopsy or FibroScan/CAP), but did not reach significance with ballooning or inflammation grades. CK18 was significantly different in nonalcoholic steatohepatitis versus non-nonalcoholic steatohepatitis patients (P=0.041). The best CK18 cutoff to detect steatosis (S≥2) in NAFLD and HCV was 11.65 and 6.84 ng/ml, respectively with an overall sensitivity and specificity over 97%. The CK18 cutoff for significant fibrosis (F≥2) by FibroScan in the NAFLD/HCV groups was 9.115 ng/ml, with 62.5%/69.2% sensitivity/specificity (P=0.031). However, inflammation had a cutoff with a marginal P value (P=0.080), and a reliable cutoff for ballooning was not attained (P=0.386). There was a positive correlation between CK18 and fibrosis (by FibroScan) in the NAFLD and HCV groups (P<0.05). The correlation between CK18 and steatosis in CAP and the nonalcoholic fatty liver disease activity score was very good (P<0.001).

CONCLUSION

Serum CK18 is related strongly to the development/progression of NAFLD and HCV-related fibrosis/steatosis. TE was correlated highly with liver biopsy results. The combination of CK18 with other noninvasive modalities increases the diagnostic yield of these tests.

When dying is not the end: Apoptotic caspases as drivers of proliferation

Caspases are well known for their role as executioners of apoptosis. However, recent studies have revealed that these lethal enzymes also have important mitogenic functions. Caspases can promote proliferation through autonomous regulation of the cell cycle, as well as by induction of secreted signals, which have a profound impact in neighboring tissues. Here, I review the proliferative role of caspases during development and homeostasis, in addition to their key regenerative function during tissue repair upon injury. Furthermore, the emerging properties of apoptotic caspases as drivers of carcinogenesis are discussed, as well as their involvement in other diseases. Finally, I examine further effects of caspases regulating death and survival in a non-autonomous manner.

LPS-TLR4 Pathway Mediates Ductular Cell Expansion in Alcoholic Hepatitis

Alcoholic hepatitis (AH) is the most severe form of alcoholic liver disease for which there are no effective therapies. Patients with AH show impaired hepatocyte proliferation, expansion of inefficient ductular cells and high lipopolysaccharide (LPS) levels. It is unknown whether LPS mediates ductular cell expansion. We performed transcriptome studies and identified keratin 23 (KRT23) as a new ductular cell marker. KRT23 expression correlated with mortality and LPS serum levels. LPS-TLR4 pathway role in ductular cell expansion was assessed in human and mouse progenitor cells, liver slices and liver injured TLR4 KO mice. In AH patients, ductular cell expansion correlated with portal hypertension and collagen expression. Functional studies in ductular cells showed that KRT23 regulates collagen expression. These results support a role for LPS-TLR4 pathway in promoting ductular reaction in AH. Maneuvers aimed at decreasing LPS serum levels in AH patients could have beneficial effects by preventing ductular reaction development.

Serum cell death biomarker mirrors liver cancer regression after transarterial chemoembolisation

BACKGROUND

Hepatocellular carcinoma (HCC) represents an increasing health problem with limited therapeutic options. In patients with intermediate disease stage, transarterial chemoembolisation (TACE) is widely applied. Treatment response is routinely assessed by imaging techniques according to the international response evaluation criteria in solid tumours (RECIST), which consider tumour regression or additionally tumour necrosis (modified RECIST). Evaluation of treatment response, however, by these methods is time- and cost-intensive and usually performed at earliest several months following TACE.

AIM

To investigate the suitability of novel non-invasive cell death biomarkers for an earlier prediction of TACE response.

METHODS

We analysed activation of pro-apoptotic caspases and the proteolytic cleavage of the caspase substrate CK-18 in liver tissues and sera from HCC patients by immunohistochemistry, a luminometric substrate assay and ELISA.

RESULTS

Both caspase activity and caspase-cleaved CK-18 fragments were elevated in HCC patients compared to healthy controls. CK-18 serum levels significantly increased during the first 3 days and peaked at day two following TACE. Interestingly, we found significant differences in CK-18 levels between patients with and without tumour regression. Detection of CK-18 fragments revealed a promising performance for the early prediction of TACE response with an area under the curve value of 0.76.

CONCLUSIONS

Caspase-cleaved CK-18 levels mirror liver cancer regression and allow an earlier prediction of TACE response. The concordance with mRECIST suggests that the detection of CK-18 levels immediately after TACE might be used as a short-term decision guide to continue or change HCC therapy.

Low levels of Caspase-3 predict favourable response to 5FU-based chemotherapy in advanced colorectal cancer: Caspase-3 inhibition as a therapeutic approach

Colorectal cancer (CRC) is one of the most common cancers in the Western world. 5-Fluorouracil (5FU)-based chemotherapy (CT) remains the mainstay treatment of CRC in the advanced setting, and activates executioner caspases in target cells. Executioner caspases are key proteins involved in cell disassembly during apoptosis. Activation of executioner caspases also has a role in tissue regeneration and repopulation by stimulating signal transduction and cell proliferation in neighbouring, non-apoptotic cells as reported recently. Tissue microarrays (TMAs) consisting of tumour tissue from 93 stage II and III colon cancer patients were analysed by immunohistochemistry. Surprisingly, patients with low levels of active Caspase-3 had an increased disease-free survival time. This was particularly pronounced in patients who received 5FU-based adjuvant CT. In line with this observation, lower serum levels of active Caspase-3 were found in patients with metastasised CRC who revealed stable disease or tumour regression compared with those with disease progression. The role of Caspase-3 in treatment responses was explored further in primary human tumour explant cultures from fresh patient tumour tissue. Exposure of explant cultures to 5FU-based CT increased the percentage of cells positive for active Caspase-3 and Terminal Deoxynucleotidyl Transferase dUTP Nick end Labelling (TUNEL), but also the expression of regeneration and proliferation markers β-Catenin and Ki-67, as well as cyclooxygenase-2 (COX-2). Of note, selective inhibition of Caspase-3 with Ac-DNLD-CHO, a selective, reversible inhibitor of Caspase-3, significantly reduced the expression of proliferation markers as well as COX-2. Inhibition of COX-2 with aspirin or celecoxib did not affect Caspase-3 levels but also reduced Ki-67 and β-Catenin levels, suggesting that Caspase-3 acted via COX-2 to stimulate cell proliferation and tissue regeneration. This indicates that low levels of active Caspase-3 may represent a new predictor of CT responsiveness, and inhibition of Caspase-3, or antagonising downstream effectors of Caspase-3 paracrine signalling, such as COX-2 may improve patient outcomes following CT in advanced CRC.

Chronic hepatitis C virus infection: Serum biomarkers in predicting liver damage

Currently, a major clinical challenge in the management of the increasing number of hepatitis C virus (HCV) infected patients is determining the best means for evaluating liver impairment. Prognosis and treatment of chronic hepatitis C (CHC) are partly dependent on the assessment of histological activity, namely cell necrosis and inflammation, and the degree of liver fibrosis. These parameters can be provided by liver biopsy; however, in addition to the risks related to an invasive procedure, liver biopsy has been associated with sampling error mostly due to suboptimal biopsy size. To avoid these pitfalls, several markers have been proposed as non-invasive alternatives for the diagnosis of liver damage. Distinct approaches among the currently available non-invasive methods are (1) the physical ones based on imaging techniques; and (2) the biological ones based on serum biomarkers. In this review, we discuss these approaches with special focus on currently available non-invasive serum markers. We will discuss: (1) class I serum biomarkers individually and as combined panels, particularly those that mirror the metabolism of liver extracellular matrix turnover and/or fibrogenic cell changes; (2) class II biomarkers that are indirect serum markers and are based on the evaluation of common functional alterations in the liver; and (3) biomarkers of liver cell death, since hepatocyte apoptosis plays a significant role in the pathogenesis of HCV infection. We highlight in this review the evidence behind the use of these markers and assess the diagnostic accuracy as well as advantages, limitations, and application in clinical practice of each test for predicting liver damage in CHC.

Cytokeratin 18-Aspartate396 apoptotic fragment for fibrosis detection in patients with non-alcoholic fatty liver disease and chronic viral hepatitis

BACKGROUND

The combination of non-invasive markers for the detection of fibrosis in patients with chronic liver diseases is still a matter of debate.

AIMS

To test the performance of cytokeratin18-Aspartate396 alone or in combination with transient elastography as a marker of fibrosis, compared to liver biopsy as gold standard.

METHODS

In 259 prospectively enrolled patients with chronic liver diseases, clinical, biochemical, and histological features were assessed. Serum cytokeratin18-Aspartate396 and Fibroscan were performed within 6 months prior to liver biopsy.

RESULTS

Cytokeratin18-Aspartate396 levels predicted both significant and advanced fibrosis in non-alcoholic fatty liver disease group, correctly identifying 83.7% and 80.8% of cases, respectively. Liver stiffness performed best in predicting severe fibrosis in patients with chronic viral infection, correctly identifying 78.7% of chronic hepatitis B and 88.6% of chronic hepatitis C subjects. The combination of cytokeratin18-Aspartate396 and liver stiffness improved their diagnostic performance for the detection of significant and advanced fibrosis in non-alcoholic fatty liver disease group, only (sensitivity=78.3%, specificity=90.7%; sensitivity=91.7%, specificity=71.6%, respectively).

CONCLUSION

Cytokeratin18-Aspartate396 and liver stiffness can improve the non-invasive prediction of significant and advanced fibrosis in patients with non-alcoholic fatty liver disease, while in hepatitis B and C virus infected patients their combined use had no advantage over the diagnostic accuracy of transient elastography alone.

Serum levels of ET-1, M30, and angiopoietins-1 and -2 in HELLP syndrome and preeclampsia compared to controls

PURPOSE

We aimed to compare the serum levels of ET-1, M30, and Angs-1 and -2 in patients with preeclampsia or HELLP syndrome, and normal controls.

METHODS

In this cross-sectional study of 74 pregnant women, serum levels of ET-1, M30, and Angs-1 and -2 were measured in preeclamptic patients with or without HELLP syndrome. 74 pregnant women; 37 had healthy pregnancies, 25 had preeclampsia (PE), and 12 had HELLP syndrome.

RESULTS

The age, body mass index, gravidity, and parity of patients with normal pregnancy, PE, and HELLP syndrome were comparable (p > 0.05). In HELLP syndrome, compared to healthy or preeclamptic pregnancies, platelet count was lower (p < 0.05) and the values of hepatic function tests were higher (p < 0.05). In HELLP syndrome, ET-1, M30, and Ang-2 were higher compared to healthy or preeclamptic pregnancies (p < 0.05); however, they increased in preeclamptic pregnancies compared to healthy pregnancies though not significant (p > 0.05). In PE or HELLP syndrome, Ang-1 was higher compared to a healthy pregnancy (p < 0.05); however, in HELLP syndrome, it was also higher than in PE though not significant (p > 0.05). We found no significant correlation among these biomarkers and hematological and biochemical parameters (p > 0.05).

CONCLUSION

For the diagnosis of HELLP syndrome, increased levels of ET-1, M30, and Angs-1 and -2 appear as promising biomarkers after determination of their standardized threshold levels after further studies. As an apoptosis-related biomarker, serum M30 level has a merit to be the most promising test for prediction or differential diagnosis of HELLP syndrome in PE patients.

Serum cell death biomarkers for prediction of liver fibrosis and poor prognosis in primary biliary cirrhosis

The development of simple, noninvasive markers of liver fibrosis is urgently needed for primary biliary cirrhosis (PBC). This study examined the ability of several serum biomarkers of cell death to estimate fibrosis and prognosis in PBC. A cohort of 130 patients with biopsy-proven PBC and 90 healthy subjects were enrolled. We assessed the utility of the M30 ELISA, which detects caspase-cleaved cytokeratin-18 (CK-18) fragments and is representative of apoptotic cell death, as well as the M65 and newly developed M65 Epideath (M65ED) ELISAs, which detect total CK-18 as indicators of overall cell death, in predicting clinically relevant fibrosis stage. All 3 cell death biomarkers were significantly higher in patients with PBC than in healthy controls and were significantly correlated with fibrosis stage. The areas under the receiver operating characteristic curve for the M65 and M65ED assays for differentiation among significant fibrosis, severe fibrosis, and cirrhosis were 0.66 and 0.76, 0.66 and 0.73, and 0.74 and 0.82, respectively. In multivariate analysis, high M65ED (hazard ratio 6.13; 95% confidence interval 1.18-31.69; P = 0.031) and severe fibrosis (hazard ratio 7.45; 95% confidence interval 1.82-30.51; P = 0.005) were independently associated with liver-related death, transplantation, or decompensation. High serum M65ED was also significantly associated with poor outcome in PBC (log-rank test; P = 0.001). Noninvasive cell death biomarkers appear to be clinically useful in predicting fibrosis in PBC. Moreover, the M65ED assay may represent a new surrogate marker of adverse disease outcome.

Distinctive intrahepatic characteristics of paediatric and adult pathogenesis of chronic hepatitis C infection

Mechanisms leading to liver damage in chronic hepatitis C (CHC) are being discussed, but both the immune system and the virus are involved. The aim of this study was to evaluate intrahepatic viral infection, apoptosis and portal and periportal/interface infiltrate in paediatric and adult patients to elucidate the pathogenesis of chronic hepatitis C. HCV-infected, activated caspase-3(+) and TUNEL(+) hepatocytes, as well as total, CD4(+), CD8(+), Foxp3(+) and CD20(+) lymphocytes infiltrating portal and periportal/interface tracts were evaluated in 27 paediatric and 32 adult liver samples by immunohistochemistry or immunofluorescence. The number of infected hepatocytes was higher in paediatric than in adult samples (p 0.0078). In children, they correlated with apoptotic hepatocytes (activated caspase-3(+) r = 0.74, p < 0.0001; TUNEL(+) r = 0.606, p 0.0017). Also, infected (p = 0.026) and apoptotic hepatocytes (p = 0.03) were associated with the severity of fibrosis. In adults, activated caspase-3(+) cell count was increased in severe hepatitis (p = 0.009). Total, CD4(+), CD8(+) and Foxp3(+) lymphocyte count was higher in adult samples (p < 0.05). Paediatric CD8(+) cells correlated with infected (r = 0.495, p 0.04) and TUNEL(+) hepatocytes (r = 0.474, p = 0.047), while adult ones correlated with activated caspase-3(+) hepatocytes (r = 0.387, p 0.04). In adults, CD8(+) was associated with hepatitis severity (p < 0.0001) and correlated with inflammatory activity (CD8(+) r = 0.639, p 0.0003). HCV, apoptosis and immune response proved to be involved in CHC pathogenesis of both paediatric and adult patients. However, liver injury in paediatric CHC would be largely associated with a viral cytopathic effect mediated by apoptosis, while in adults it would be mainly associated with an exacerbated immune response.

Biomarkers of liver cell death

Hepatocyte cell death during liver injury was classically viewed to occur by either programmed (apoptosis), or accidental, uncontrolled cell death (necrosis). Growing evidence from our increasing understanding of the biochemical and molecular mechanisms involved in cell demise has provided an expanding view of various modes of cell death that can be triggered during both acute and chronic liver damage such as necroptosis, pyroptosis, and autophagic cell death. The complexity of non-invasively assessing the predominant mode of cell death during a specific liver insult in either experimental in vivo models or in humans is highlighted by the fact that in many instances there is significant crosstalk and overlap between the different cell death pathways. Nevertheless, the realization that during cell demise triggered by a specific mode of cell death certain intracellular molecules such as proteins, newly generated protein fragments, or MicroRNAs are released from hepatocytes into the extracellular space and may appear in circulation have spurred a significant interest in the development of non-invasive markers to monitor liver cell death. This review focuses on some of the most promising markers, and their potential role in assessing the presence and severity of liver damage in humans.

Increased plasma levels of CK-18 as potential cell death biomarker in patients with HELLP syndrome

HELLP (hemolysis, elevated liver enzymes, low platelets) syndrome represents a life-threatening pregnancy disorder with high fetal and maternal mortality, but its underlying molecular mechanisms remain unknown. Although apoptosis has been implicated in HELLP syndrome, its pathogenic role remains largely unclear. In the present study, we investigated whether the detection of apoptosis by novel plasma biomarkers is of diagnostic value in HELLP patients. For this purpose, we analyzed two biomarkers that specifically detect apoptosis or overall cell death of epithelial cells, such as hepatocytes or placental trophoblasts, through the release of caspase-cleaved or total (caspase-cleaved and uncleaved) cytokeratin-18 (CK-18) in plasma of HELLP patients compared with pregnant as well as non-pregnant healthy women. In addition, caspase activation and cell death were determined in placental tissues of HELLP patients and individuals with normal pregnancy. In contrast to pregnant or non-pregnant healthy controls, we observed significantly increased levels of both caspase-cleaved and total CK-18 in plasma of HELLP patients. Following delivery, CK-18 levels rapidly decreased in HELLP patients. Caspase activation and cell death were also elevated in placental tissues from HELLP patients compared with healthy pregnant women. These data demonstrate not only that apoptosis is increased in HELLP syndrome, but also that caspase-cleaved or total CK-18 are promising plasma biomarkers to identify patients with HELLP syndrome. Thus, further studies are warranted to evaluate the utility of these biomarkers for monitoring disease activity in HELLP syndrome.

Metabolic factors and chronic hepatitis C: a complex interplay

In the last years, several lines of evidence showed how metabolic factors may influence the natural history of patients with chronic hepatitis C. Chronic HCV infection is able to perturb the metabolic homeostasis of the host, in a context of complex interactions where pre-existent metabolic status and genetic background play an important role, allowing us to state that HCV infection is a systemic disease. In this review, we discuss the most recent lines of evidence on the main metabolic factors that are known to be associated with CHC, namely, insulin resistance/type 2 diabetes, steatosis, visceral obesity, atherosclerosis, vitamin D, menopause, fructose and coffee intake, lipoproteins, methylenetetrahydrofolate reductase status, and hyperuricaemia. In particular, we focus on the pathophysiological mechanisms underlying the correlation between HCV infection and metabolic disorders, the impact of metabolic factors on the progression of liver and non-liver-related diseases, and, on the contrary, the possible influence of chronic HCV infection on metabolic features. In this setting, the importance of a multifaceted evaluation of CHC patients and a prompt correction of modifiable metabolic risk factors should be emphasized.

The predictive value of steatosis in hepatitis C virus infection

Steatosis is a complication of hepatitis C virus (HCV) infection and the mechanisms of its development are complex, involving viral and host factors. Steatosis that is prevalently viral is associated with HCV genotype 3, and steatosis that is prevalently metabolic is associated with non-3 genotypes. Viral steatosis is correlated with the level of HCV replication, whereas metabolic steatosis is related to insulin resistance. The two types of steatosis have a different impact on HCV disease and may have an additive effect. HCV infection is a multifaceted disease with hepatic and extrahepatic manifestations. There is a body of evidence indicating that HCV-related steatosis plays a role in many HCV manifestations and, thus, the presence of steatosis is a predictive factor for the development of such events. The current data show that HCV-related steatosis predicts an advanced liver disease and a more rapid progression of fibrosis, as well as an increased risk of development of hepatocellular carcinoma. Moreover, the presence of steatosis in a HCV patient has a high predictive value that the subject may have or may develop insulin resistance, diabetes and metabolic syndrome. Recently, a strict association between HCV-related steatosis and development of atherosclerosis has been demonstrated. In addition, steatosis negatively impacts response rate to interferon-based treatment, even in HCV genotype-3 infection. Therapeutic strategies to improve steatosis and, consequently, response to standard antiviral therapy and outcome of disease are wanted. The authors summarize current knowledge of impact of steatosis on the above reported clinical conditions associated with HCV infection.

Increased apoptosis induction in hepatocellular carcinoma by a novel tumor-targeted TRAIL fusion protein combined with bortezomib

As the result of an increasing incidence and a prevalent therapy resistance of hepatocellular carcinoma (HCC), there is a strong need for novel strategies to enhance treatment responses in HCC. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has been proposed as a promising anticancer drug because it can selectively induce apoptosis in cancer cells, but not in healthy cells. Nevertheless, most tumor cells show TRAIL resistance, emphasizing the requirement for apoptosis-sensitizing agents and TRAIL molecules with improved tumor specificity. In this study, we employed a recombinant TRAIL molecule, in which three TRAIL protomers were expressed as a single polypeptide chain (scTRAIL), and a novel TRAIL variant, in which scTRAIL was additionally fused to an antibody fragment recognizing epidermal growth factor receptor (EGFR) to improve its HCC-targeting properties. We analyzed the proapoptotic effects of both TRAIL versions in combination with the proteasome inhibitor bortezomib (BZB) in hepatoma cells and primary human hepatocytes as well as in intact explants from HCC and healthy liver tissue. We demonstrate that EGFR-targeted TRAIL in combination with BZB induced significantly higher caspase activation and cell death in hepatoma cells, but not in primary hepatocytes. Importantly, when incubated with fresh liver explants, the combination of EGFR-targeted TRAIL and BZB displayed selective cytotoxicity for HCC, but not for tumor-free liver tissue, which could even be verified in liver explants from the same individuals. Unlike nontargeted TRAIL, EGFR-targeted TRAIL combined with BZB exerted no toxicity in liver tissues from nonalcoholic fatty liver disease patients.

CONCLUSION

EGFR-targeted TRAIL reveals increased antitumor activity toward HCC without inducing toxicity to tumor-free liver tissue and might therefore represent a promising novel strategy for HCC treatment.

Serum apoptosis markers related to liver damage in chronic hepatitis C: sFas as a marker of advanced fibrosis in children and adults while M30 of severe steatosis only in children

Background

Liver biopsy represents the gold standard for evaluating damage and progression in patients with chronic hepatitis C (CHC); however, developing noninvasive tests that can predict liver injury represents a growing medical need. Considering that hepatocyte apoptosis plays a role in CHC pathogenesis; the aim of our study was to evaluate the presence of different apoptosis markers that correlate with liver injury in a cohort of pediatric and adult patients with CHC.

Methods

Liver biopsies and concomitant serum samples from 22 pediatric and 22 adult patients with CHC were analyzed. Histological parameters were evaluated. In serum samples soluble Fas (sFas), caspase activity and caspase-generated neoepitope of the CK-18 proteolytic fragment (M30) were measured.

Results

sFas was associated with fibrosis severity in pediatric (significant fibrosis p = 0.03, advanced fibrosis p = 0.01) and adult patients (advanced fibrosis p = 0.02). M30 levels were elevated in pediatric patients with severe steatosis (p = 0.01) while in adults no relation with any histological variable was observed. Caspase activity levels were higher in pediatric samples with significant fibrosis (p = 0.03) and they were associated with hepatitis severity (p = 0.04) in adult patients. The diagnostic accuracy evaluation demonstrated only a good performance for sFas to evaluate advanced fibrosis both in children (AUROC: 0.812) and adults (AUROC: 0.800) as well as for M30 to determine steatosis severity in children (AUROC: 0.833).

Conclusions

Serum sFas could be considered a possible marker of advanced fibrosis both in pediatric and adult patient with CHC as well as M30 might be a good predictor of steatosis severity in children.

Liver biopsy in modern clinical practice: a pediatric point-of-view

Liver biopsy remains the foundation of evaluation and management of liver disease in children, although the role of the liver biopsy is changing with development of alternative methods of diagnosis and advancement of hepatic imaging techniques. The indications for liver biopsy are evolving as current knowledge of etiologies, noninvasive biomarker alternatives, and treatment options in pediatric liver disease are expanding. The procedure can often be complicated in children by technical difficulties, cost, and smaller specimen size. Communication and partnership of clinicians with pathologists experienced in pediatric liver diseases are essential. DNA sequencing, novel imaging modalities, noninvasive biomarkers of fibrosis and apoptosis, proteomics, and genome-wide association studies offer potential alternative methods for evaluation of liver disease in children. This review presents specific indications, considerations, methods, complications, contraindications, and alternatives for pediatric liver biopsy.

Superior antitumoral activity of dimerized targeted single-chain TRAIL fusion proteins under retention of tumor selectivity

Although targeting of the death receptors (DRs) DR4 and DR5 still appears a suitable antitumoral strategy, the limited clinical responses to recombinant soluble TNF-related apoptosis inducing ligand (TRAIL) necessitate novel reagents with improved apoptotic activity/tumor selectivity. Apoptosis induction by a single-chain TRAIL (scTRAIL) molecule could be enhanced >10-fold by generation of epidermal growth factor receptor (EGFR)-specific scFv-scTRAIL fusion proteins. By forcing dimerization of scFv-scTRAIL based on scFv linker modification, we obtained a targeted scTRAIL composed predominantly of dimers (Db-scTRAIL), exceeding the activity of nontargeted scTRAIL ∼100-fold on Huh-7 hepatocellular and Colo205 colon carcinoma cells. Increased activity of Db-scTRAIL was also demonstrated on target-negative cells, suggesting that, in addition to targeting, oligomerization equivalent to an at least dimeric assembly of standard TRAIL per se enhances apoptosis signaling. In the presence of apoptosis sensitizers, such as the proteasomal inhibitor bortezomib, Db-scTRAIL was effective at picomolar concentrations in vitro (EC(50) ∼2 × 10(-12) M). Importantly, in vivo, Db-scTRAIL was well tolerated and displayed superior antitumoral activity in mouse xenograft (Colo205) tumor models. Our results show that both targeting and controlled dimerization of scTRAIL fusion proteins provides a strategy to enforce apoptosis induction, together with retained tumor selectivity and good in vivo tolerance.

Mechanisms of cell death in acute liver failure

Acute liver failure (ALF) can be the consequence of various etiologies, that might vary between different geographic regions. Most frequent are intoxications with acetaminophen, viral hepatitis, or liver damage of unknown origin. ALF occurs when the extent of hepatocyte death exceeds the regenerative capacity of the liver. The mode of liver cell death that is predominantly induced in ALF, i.e., apoptosis or necrosis, is still controversial and presumably determined by the etiology, duration, and magnitude of liver injury. Severe liver damage involves oxidative stress and depletion of ATP resulting in necrosis. In contrast, maintenance of ATP stores is required for the execution of apoptosis. Recent data suggest that necrosis resulting from severe liver damage is associated with poor outcome of ALF patients. Discrimination between apoptosis and necrosis might be therefore useful for the identification of ALF patients requiring liver transplantation. Identification of the molecular cell death mechanisms remains an important issue not only for early prediction of ALF outcome, but also for therapeutic interventions. In view of the pleiotropic functions of critical mediators of cell death and tissue regeneration, a particular challenge will be to reduce hepatocellular death without inhibiting the regenerative capacity of the liver. Here, we review the molecular mechanisms of hepatocyte injury and the pathways leading to apoptosis and necrosis, which might represent potential diagnostic and therapeutic targets in ALF.

Elevated serum CK18 levels in chronic hepatitis C patients are associated with advanced fibrosis but not steatosis

Cytokeratin-18 (CK-18) is a major intermediate filament protein in liver cells. The M30 fragment of CK-18 has been identified as a useful marker of apoptosis associated with fibrosis and steatosis in nonalcoholic steatohepatitis (NASH). We sought to assess the relationship of this marker and steatosis in a cohort of adult patients with chronic hepatitis C. The study cohort included sera from 267 treatment-naïve chronic hepatitis C (CHC) patients and 100 healthy controls with normal alanine aminotransferase (ALT). Biopsies from CHC patients were assessed for METAVIR fibrosis stage, Histology Activity Index (HAI) inflammation score and steatosis grade by expert histopathologists. The M30 fragment of CK-18 was quantified by ELISA. Wilcoxon Rank Sum, Spearman Correlation and Linear Regression tests were performed for statistical analysis. Median CK-18 levels were higher in CHC patients compared to controls (411 vs 196 U/L, P < 0.0001). Fibrosis stage was associated with increasing serum CK-18 levels (P = 0.015) and CK-18 levels were higher for F2-F4 vs F0-F1 (500 vs 344 U/L; P = 0.001). There was no association between CK-18 and increasing steatosis grade 1, 2 or 3 (460.7 vs 416.8 vs 508.3 U/L; P = 0.35) and presence or absence of steatosis (445.3 vs 365.8 U/L; P = 0.075). Fibrosis stage was independently associated with serum M30 in a multivariable linear regression model (P = 0.03). CK-18 levels were higher in CHC compared to healthy controls and associated with hepatic fibrosis. There was no difference in CK-18 M30 levels between CHC patients with and without steatosis. Although apoptosis may still contribute to hepatitis C virus (HCV)-mediated steatosis, our results suggest that serum CK-18 will not be a clinically useful test for identifying significant steatosis in CHC.

Prospective biopsy-controlled evaluation of cell death biomarkers for prediction of liver fibrosis and nonalcoholic steatohepatitis

Fibrosis and steatosis are major histopathological alterations in chronic liver diseases. Despite various shortcomings, disease severity is generally determined by liver biopsy, emphasizing the need for simple noninvasive methods for assessing disease activity. Because hepatocyte cell death is considered a crucial pathogenic factor, we prospectively evaluated the utility of serum biomarkers of cell death to predict different stages of fibrosis and steatosis in 121 patients with chronic liver disease. We compared the M30 enzyme-linked immunosorbent assay (ELISA), which detects a caspase-cleaved cytokeratin-18 (CK-18) fragment and thereby apoptotic cell death, with the M65 ELISA, which detects both caspase-cleaved and uncleaved CK-18 and thereby overall cell death. Both biomarkers significantly discriminated patients with different fibrosis stages from healthy controls. However, whereas both markers differentiated low or moderate from advanced fibrosis, only the M65 antigen could discriminate even lower stages of fibrosis. The M65 assay also performed better in distinguishing low (≤10%) and higher (>10%) grades of steatosis. In a subgroup of patients, we evaluated the biomarkers for their power to predict nonalcoholic steatohepatitis (NASH). Importantly, both markers accurately differentiated healthy controls or simple steatosis from NASH. However, only serum levels of M65 antigen could differentiate simple steatosis from healthy controls.

CONCLUSION

Cell death biomarkers are potentially useful to predict fibrosis, steatosis, or NASH. Compared with the widely used apoptosis marker M30, the M65 assay had a better diagnostic performance and even differentiated between lower fibrosis stages as well as between healthy individuals and patients with simple steatosis.

Serum fragmented cytokeratin 18 levels reflect the histologic activity score of nonalcoholic fatty liver disease more accurately than serum alanine aminotransferase levels

BACKGROUND AND GOALS

Reliable noninvasive biomarkers to assess the histologic activity of nonalcoholic fatty liver disease (NAFLD) have not been established. As the frequency of Mallory bodies is known to be closely associated with the disease severity, we hypothesized that serum levels of Mallory body-related proteins were correlated with NAFLD histologic activity and evaluated this possibility.

STUDY

Serum levels of total and fragmented cytokeratin (CK) 18, heat shock protein (Hsp) 70, Hsp90alpha, ubiquitin+1, and p38alpha at the time of liver biopsy were measured in 118 NAFLD patients and their association with histologic findings and NAFLD histologic activity score (NAS) was investigated.

RESULTS

Serum levels of both forms of CK18 and Hsp90alpha were markedly higher in patients having nonalcoholic steatohepatitis (NASH) compared with non-NASH ones. Both forms of CK18 significantly correlated with degree of steatosis, lobular inflammation, and ballooning, and showed stronger positive correlations with NAS than serum aspartate and alanine aminotransferase (AST and ALT). Multiple regression analysis further revealed that fragmented CK18 and AST were effective predictors of NAS, with the former being the more definitive of the two (P<0.001 vs. 0.005). In 20 NAFLD patients who received a follow-up biopsy, changes in fragmented CK18 levels, but not AST or ALT levels, closely paralleled those in NAS.

CONCLUSIONS

These results establish the usefulness of fragmented CK18 measurement for assessing and monitoring the histologic activity of NAFLD.

Serum apoptotic caspase activity in chronic hepatitis C and nonalcoholic Fatty liver disease

BACKGROUND

Apoptotic caspases are substantially activated in liver and serum caspase activity has been suggested as a marker of early liver injury.

AIM

To investigate whether serum levels of caspase-generated fragments of cytokeratin-18 are associated with the severity of histologic lesions in chronic hepatitis C virus (HCV) infection and nonalcoholic fatty liver disease (NAFLD).

METHODS

We included 134 patients with chronic HCV infection and 58 patients with NAFLD, who consecutively underwent liver biopsy, and 40 healthy controls. Caspase-generated cytokeratin-18 fragment levels were blindly measured in stored serum samples.

RESULTS

Median cytokeratin-18 fragment levels were lower in HCV-positive patients with minimal/mild than patients with moderate/severe histologic lesions (174 U/L vs. 223 U/L, P<0.001) offering moderate accuracy for differentiation between the 2 groups (c-statistic: 0.74). Cytokeratin-18 fragments levels were lower in healthy subjects (148 U/L) than patients with simple fatty liver (174 U/L, P=0.013) than patients with nonalcoholic steatohepatitis (355 U/L, P<0.001) offering excellent diagnostic accuracy for differentiation between the 2 latter groups (c-statistic: 0.87).

CONCLUSIONS

Serum apoptotic caspase activity is associated with the severity of liver histologic lesions in both chronic HCV infection and NAFLD, but it has excellent diagnostic accuracy in NAFLD and moderate accuracy in chronic HCV patients.

Serum biomarkers of cell death for monitoring therapy response of gastrointestinal carcinomas

PURPOSE

Antitumour treatments are thought to exert their therapeutic efficacy mainly by induction of apoptosis in tumour cells. In epithelial cells, caspases, the key enzymes of apoptosis, cleave the intermediate filament protein cytokeratin (CK)-18 into specific fragments that are released into circulating blood and can be detected by a specific ELISA.

EXPERIMENTAL DESIGN

To investigate the use of CK-18 fragments as a potential biomarker for the treatment response, we examined the association of serum CK-18 levels and clinical response in 35 patients with gastrointestinal cancers.

RESULTS

While both cleaved and total CK-18 levels were intrinsically elevated in tumour patients, they were further increased during 5-fluorouracil (5-FU)-based therapy. Importantly, the increased levels of CK-18 could discriminate between patients with different clinical response. Cancer patients with a partial response or stable disease revealed a significantly higher increase of cleaved CK-18 during chemotherapy as compared to patients with progressive disease.

CONCLUSIONS

Our results suggest that detection of circulating caspase-cleaved CK-18 might be a useful serum biomarker for monitoring treatment response and should merit further evaluation in larger patient groups.

Coinfection with HIV-1 and HCV--a one-two punch

Hepatitis C virus (HCV) infection is a major cause of chronic liver disease, cirrhosis, and death; it is estimated that 180 million persons are infected with HCV worldwide. The consequences of HCV are worse in those who are coinfected with human immunodeficiency virus 1 (HIV-1), which is unfortunately a common scenario because of shared risk factors of the viruses. More studies into effects of HCV/HIV-1 coinfection are needed, but efforts have been hampered by limitations in our understanding of the combined pathogenesis of the 2 viruses. Gaining insight into the mechanisms that underlie the immunopathogenesis of these persistent viral infections could lead to new therapeutic strategies for patients with HCV/HIV-1 coinfection.

Cell death in sepsis: a matter of how, when, and where

Dysregulated cell death in several tissues is intimately involved in the pathogenesis of sepsis and contributes to multiple organ failure. Whether cell death during sepsis occurs by necrosis or apoptosis may depend on the cell type as well as the disease stage and is therefore a matter of intense debate. While lymphocyte apoptosis contributes to immunosuppression in sepsis, recent evidence suggests that necrosis of hepatocytes predominates in septic patients with liver dysfunction and correlates with poor survival. These distinct modes of cell death might have different consequences for the inflammatory response but are also critical for therapeutic interventions and the disease outcome. Understanding the complexity of death processes employing recently available serum biomarkers of cell death could lead to novel therapeutic approaches and assist in the steering of sepsis treatment.

Hepatitis C virus and type 2 diabetes

This review focuses on the relationship between hepatitis C virus (HCV) infection and glucose metabolism derangements. Cross-sectional and longitudinal studies have shown that the chronic HCV infection is associated with an increased risk of developing insulin resistance (IR) and type 2 diabetes (T2D). The direct effect of HCV on the insulin signaling has been analyzed in experimental models. Although currently available data should be considered as preliminary, HCV seems to affect glucose metabolism via mechanisms that involve cellular pathways that have been implicated in the host innate immune response. IR and T2D not only accelerate the histological and clinical progression of chronic hepatitis C, but also reduce the early and sustained virological response to interferon-alpha-based therapy. Thus, a detailed knowledge of the mechanisms underlying the HCV-associated glucose metabolism derangements is warranted, in order to improve the clinical management of chronic hepatitis C patients.

The pharmacokinetics of silymarin is altered in patients with hepatitis C virus and nonalcoholic Fatty liver disease and correlates with plasma caspase-3/7 activity

Silymarin, used by 30 to 40% of liver disease patients, is composed of six major flavonolignans, each of which may contribute to silymarin's hepatoprotective properties. Previous studies have only described the pharmacokinetics for two flavonolignans, silybin A and silybin B, in healthy volunteers. The aim of this study was to determine the pharmacokinetics of the major silymarin flavonolignans in liver disease patients. Healthy volunteers and three patient cohorts were administered a single, 600-mg p.o. dose of milk thistle extract, and 14 blood samples were obtained over 24 h. Silybin A and B accounted for 43% of the exposure to the sum of total silymarin flavonolignans in healthy volunteers and only 31 to 38% in liver disease cohorts as a result of accumulation of silychristin (20-36%). Area under the curve (AUC(0-24h)) for the sum of total silymarin flavonolignans was 2.4-, 3.3-, and 4.7-fold higher for hepatitis C virus (HCV) noncirrhosis, nonalcoholic fatty liver disease (p <or= 0.03), and HCV cirrhosis cohorts (p <or= 0.03), respectively, compared with healthy volunteers (AUC(0-24h) = 2021 ng . h/ml). Caspase-3/7 activity correlated with the AUC(0-24h) for the sum of all silymarin conjugates among all subjects (R(2) = 0.52) and was 5-fold higher in the HCV cirrhosis cohort (p <or= 0.005 versus healthy). No correlation was observed with other measures of disease activity, including plasma alanine aminotransferase, interleukin 6, and 8-isoprostane F(2alpha), a measure of oxidative stress. These findings suggest that the pharmacokinetics of silymarin is altered in patients with liver disease. Patients with cirrhosis had the highest plasma caspase-3/7 activity and also achieved the highest exposures for the major silymarin flavonolignans.

The presence of steatosis and elevation of alanine aminotransferase levels are associated with fibrosis progression in chronic hepatitis C with non-response to interferon therapy

BACKGROUND/AIMS

Interferon (IFN) therapy leads to regression of hepatic fibrosis in chronic hepatitis C patients who achieve a sustained virologic response (SVR), while the beneficial effect is limited in those who fail to do so. The aim of the present study was to define factors associated with progression of fibrosis in patients who do not achieve a SVR.

METHODS

Fibrosis staging scores were compared between paired liver biopsies before and after IFN in 97 chronic hepatitis C patients who failed therapy. The mean interval between biopsies was 5.9 years. Factors associated with progression of fibrosis were analyzed.

RESULTS

Fibrosis progressed in 23%, remained unchanged in 47% and regressed in 29%. Steatosis and a high average alanine aminotransferase (ALT) between biopsies were independent factors for progression of fibrosis with risk ratios of 5.53 and 4.48, respectively. Incidence and yearly rate of progression of fibrosis was 64% and 0.22+/-0.29 fibrosis units per year in those with both risk factors compared to 8% and -0.04+/-0.17 fibrosis units per year in those negative for both factors.

CONCLUSIONS

Hepatic steatosis and elevated ALT levels are risk factors for progression of fibrosis in chronic hepatitis C patients who fail to achieve a SVR to IFN therapy and therefore may be therapeutic targets to halt the potentially progressive disease.

Caspase activation is associated with spontaneous recovery from acute liver failure

Acute liver failure (ALF) has various causes and is characterized by rapid hepatocyte dysfunction with development of encephalopathy in the absence of preexisting liver disease. Whereas most patients require liver transplantation to prevent the high mortality, some patients recover spontaneously and show complete liver regeneration. Because of the low incidence of ALF, however, the molecular mechanisms of liver dysfunction and regeneration are largely unknown. In this study, we investigated the role of apoptosis and caspases in 70 ALF patients using novel biomarkers that allow the detection of caspase activation in serum samples. Compared with healthy individuals, activation of caspases was strongly enhanced in ALF patients. Interestingly, patients with spontaneous recovery from ALF revealed a significantly higher activation of caspases than patients that required transplantation or died, although in the latter patients extensive DNA fragmentation and signs of nonapoptotic cell death were observed. In the spontaneous survivors, increased caspase activation was accompanied by elevated levels of tumor necrosis factor alpha (TNF-alpha) and interleukin-6 (IL-6), important cytokines involved in liver regeneration.

CONCLUSION

Our data suggest that caspase activation and apoptosis are involved in ALF of patients with spontaneous recovery, whereas caspase-independent cell death might be more relevant in irreversible forms of liver failure. These findings might be important for therapeutic options of ALF but also suggest that measurement of caspase activation might be of prognostic value to predict the outcome of acute liver failure.

Steatosis correlates with hepatic expression of death receptors and activation of nuclear factor-kappaB in chronic hepatitis C

BACKGROUND

Steatosis is recognized as a predictor of the severity as well as the progression of fibrosis in chronic hepatitis C. The mechanisms that cause increased hepatocellular injury associated with steatosis remain largely unknown.

METHODS

We studied the correlation of hepatic expression of death receptors: Fas and tumour necrosis factor-alpha receptor 1 (TNF-R1), and downstream caspase (caspase-3) with hepatic steatosis by immunohistochemical study in chronic hepatitis C and determined the role of nuclear factor-kappaB (NF-kappaB).

RESULTS

Ninety patients (49 males and 41 females, mean age of 50.5 +/- 10.4 years, genotype 1 or 2) with chronic hepatitis C virus infection were recruited. The factors associated with steatosis grade were body mass index (P=0.004) and fibrosis stage (P=0.034). Moderate/severe steatosis was an independent variable associated with advanced fibrosis stage by stepwise logistic regression analysis. The expression of immunoreactivity for Fas, TNF-R1 and active caspases-3 in liver tissues was significantly correlated with the steatosis grade (P<0.001, P<0.001 and P<0.001 respectively). The extent of active caspases-3 correlated significantly with the expression of Fas (r=0.659, P<0.001) and TNF-R1 (r=0.617, P<0.001). NF-kappaB p65 expression correlated significantly with the extent of Fas (r=0.405, P<0.001), TNF-R1 (r=0.448, P=0.002) and active caspase-3 (r=0.313, P=0.003), and correlated with steatosis grade (P<0.001) but not with inflammatory and fibrosis scores.

CONCLUSION

Our observations suggest a mechanism whereby steatosis contributes to the progression of liver injury in chronic hepatitis C through upregulation of death receptors and activation of NF-kappaB.

Increased hepatotoxicity of tumor necrosis factor-related apoptosis-inducing ligand in diseased human liver

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces apoptosis in tumor cells but not in most normal cells and has therefore been proposed as a promising antitumor agent. Recent experiments suggested that isolated primary human hepatocytes but not monkey liver cells are susceptible to certain TRAIL agonists, raising concerns about the use of TRAIL in cancer treatment. Whether TRAIL indeed exerts hepatotoxicity in vivo and how this is influenced by chemotherapeutic drugs or liver disease are completely unknown. Employing different forms of recombinant TRAIL, we found that the cytokine can induce proapoptotic caspase activity in isolated human hepatocytes. However in marked contrast, these different TRAIL preparations induced little or no cytotoxicity when incubated with tissue explants of fresh healthy liver, an experimental model that may more faithfully mimic the in vivo situation. In healthy liver, TRAIL induced apoptosis only when combined with histone deacetylase inhibitors. Strikingly, however, TRAIL alone triggered massive apoptosis accompanied by caspase activation in tissue explants from patients with liver steatosis or hepatitis C viral infection. This enhanced sensitivity of diseased liver was associated with an increased expression of TRAIL receptors and up-regulation of proapoptotic Bcl-2 proteins.

CONCLUSION

These results suggest that clinical trials should be performed with great caution when TRAIL is combined with chemotherapy or administered to patients with inflammatory liver diseases.

Cre-estrogen receptor-mediated hepatitis C virus structural protein expression in mice

Hepatocyte apoptosis is an important feature of liver injury in hepatitis C virus (HCV) infection. However, the mechanism of apoptosis and consequences on disease progression in vivo have not been investigated fully in part due to the lack of adequate small animal models. In this study, transgenic (tg) mice were produced that express conditionally HCV structural proteins (core, E1, E2 and p7) in the liver following Cre-mediated DNA recombination. Using a novel Cre-estrogen receptor fusion protein (Cre-ER) induction strategy, tamoxifen was injected intraperitoneally (i.p.), which induced Cre nuclear translocation, transgene recombination and HCV protein expression in the liver. Hepatic expression of HCV core and envelope proteins resulted in increased hepatocyte apoptosis, detected by the TUNEL assay, between 7 and 33 days after induction. These results were confirmed by the presence of increased levels of apoptosis-associated cytokeratin 18 (CK-18) in the sera of the same animals. The presence of cleaved caspase-3 and elevated levels of CHOP/GADD153 in the liver suggests an endoplasmic reticulum (ER) stress-associated apoptosis mechanism. This study suggests an in vivo correlation between HCV structural protein expression, ER stress and hepatocyte apoptosis, implicating a potentially important mechanism of HCV pathogenesis.

Dynamics of Apoptotic Activity during Antiviral Treatment of Patients with Chronic Hepatitis C

Introduction

Cell death during antiviral therapy of patients with chronic hepatitis C is not well understood.

Methods

In the present study, apoptotic activity was monitored by quantification of apoptotic cytokeratin-18 neoepitopes in serum from patients with chronic hepatitis C before and 4, 12, 24 and 48 weeks after initiation of antiviral therapy with pegylated interferon-α2a and ribavirin and was compared with viral kinetic parameters.

Results

After 4 weeks of treatment apoptotic activity decreased significantly compared with baseline. Later during treatment, however, apoptotic activity increased again to levels similar to baseline. Alanine aminotransferase (ALT) activity also showed a significant decrease at week 4 compared with baseline but, in contrast to apoptotic activity, ALT remained at a reduced level during the treatment period. Baseline apoptotic activity was inversely correlated with the infected cell loss while an increase of apoptotic activity within the first 4 treatment weeks compared with baseline was positively correlated with the infected cell loss.

Conclusions

Apoptosis appears to be an important form of cell death during interferon-α-based treatment and is associated with infected cell loss and underestimated by ALT activity.

Elevated apoptosis-associated cytokeratin 18 fragments (CK18Asp386) in serum of patients with chronic liver diseases indicate hepatic and biliary inflammation

OBJECTIVES

During apoptosis, intermediate filament protein cytokeratin 18 (CK18) is cleaved by caspases at Asp396 which can be specifically detected by the monoclonal antibody M30 (M30-antigen).

DESIGN AND METHODS

M30-antigen serum levels were analyzed in 76 chronic liver diseases (CLD) patients and 62 healthy controls.

RESULTS

M30-antigen levels were significantly elevated in CLD patients (median 296.3 U/L) compared with healthy controls (median 153.5 U/L, P<0.001) and increased with disease severity (Child-Pugh or MELD score). M30-antigen correlated with aminotransferase activities and parameters indicating cholestasis such as bile acids. Highest serum M30-antigen was associated with histologically confirmed severe intrahepatic cholestasis (median 599.1 U/L) or biliary duct inflammation (median 648.0 U/L). Furthermore, in contrast to patients with liver cirrhosis, presence of hepatocellular carcinoma was associated with elevated M30-antigen in patients without cirrhosis.

CONCLUSION

Serum M30-antigen levels are elevated in CLD and correlate with hepatic inflammation as well as cholangitis and cholestasis.

Cytokeratin Markers Come of Age

Cytokeratins have been extensively used as serum tumour markers for monitoring of disease progression in cancer patients. The source of cytokeratins in the circulation as well as the mechanisms of release from cells have long been unclear. Recent evidence suggests that cytokeratins present in the circulation of cancer patients are released from apoptotic or necrotic tumour cells. CK18 is cleaved by caspases during apoptosis and a monoclonal antibody (M30) specific to caspase-cleaved forms is available. The molecular form of CK18 released from cells (caspase-cleaved or not) can conveniently be determined by immunoassays (M30-Apoptosense and M65 ELISA assays; Peviva AB, Bromma, Sweden) to determine cell death mode--apoptosis or necrosis. Recent studies where these assays were used to evaluate the response to cytotoxic anticancer drugs using cancer patient serum have been encouraging. CK18 is attracting considerable interest as a response biomarker during clinical trials of anticancer drugs. Properties such as excellent antigen stability and the epithelial specificity of cytokeratins contribute to make this biomarker attractive.

Mechanisms and significance of liver steatosis in hepatitis C virus infection

The pathogenesis of liver damage associated with chronic hepatitis C virus (HCV) infection is thought to be largely immunomediated. However, some frequent histopathological features, such as steatosis, suggest a direct cytopathic effect of HCV. The direct responsibility of HCV in the pathogenesis of steatosis is shown by: (1) the association with HCV genotype 3 infection, suggesting that some viral sequences are involved in the intracellular accumulation of lipids; (2) the correlation between severity of steatosis and HCV replication levels; (3) association between response to treatment and disappearance of steatosis. Experimental studies have shown that the nucleocapsid protein of HCV (core protein) is capable and sufficient to induce lipid accumulation in hepatocytes. Moreover, the observation that chronic hepatitis C patients have reduced serum levels of ApoB suggests an interference with the very-low density lipoprotein (VLDL) assembly, although other mechanisms are possible. In patients with sustained virological response induced by antiviral therapy, such levels are normalized. Other observations suggest that the pathogenesis of steatosis in chronic hepatitis C is not solely due to HCV. The origin of the mild steatosis observed in most patients may be metabolic, since its severity correlates with body mass index and insulin resistance. Most studies have shown a correlation between presence and/or severity of steatosis and fibrosis stage, but it is unclear whether this effect is direct or mediated by the associated insulin resistance, increased susceptibility to apoptosis, or by inflammatory cytokines. Finally, steatosis negatively influences the rate of response to antiviral treatment, as confirmed by large clinical trials. Management of steatosis in chronic hepatitis C requires knowledge of its pathogenesis and may involve both life-style changes and pharmacological interventions, although the latter remain largely experimental.

In vivo assessment of liver cell apoptosis as a novel biomarker of disease severity in nonalcoholic fatty liver disease

In patients with nonalcoholic fatty liver disease (NAFLD), a liver biopsy remains the only reliable way to differentiate simple steatosis from nonalcoholic steatohepatitis (NASH). Noninvasive methods are urgently needed. Increasing evidence suggests hepatocyte apoptosis is a key mediator of liver injury in NAFLD. The aim of this study was to quantify hepatocyte apoptosis in plasma from patients with NAFLD and correlate it with histological severity. Plasma was obtained from 44 consecutive patients with suspected NAFLD at the time of liver biopsy. Histology was assessed blindly. Caspase-3-generated cytokeratin-18 fragments were measured in situ via immunohistochemistry and in vivo using a novel enzyme-linked immunosorbent assay. Plasma cytokeratin-18 fragments were markedly increased in patients with NASH compared with patients with simple steatosis or normal biopsies (median [interquartile range]: 765.7 U/L [479.6-991.1], 202.4 U/L [160.4-258.2], 215.5 U/L [150.2-296.2], respectively; P < .001). Cytokeratin-18 fragment levels independently predicted NASH (OR 1.95; 95% CI 1.18-3.22; P = .009 for every 50 U/L increase). A cutoff value of 395 U/L calculated using the receiver operating characteristic curve approach showed a specificity of 99.9%, a sensitivity of 85.7%, and positive and negative predictive values of 99.9% and 85.7%, respectively, for the diagnosis of NASH. In conclusion, these findings strongly suggest that determination of hepatocyte caspase activation in the blood is a strong and independent predictor of NASH in human subjects. These data highlight the potential usefulness of this test as a noninvasive diagnostic means of determining histological disease severity in patients with NAFLD.

Caspase activation is required for antiviral treatment response in chronic hepatitis C virus infection

Only half of patients with chronic hepatitis C virus (HCV) infection and genotype-1 show a sustained antiviral response to the current antiviral therapy. The reason this treatment fails is unclear, and no reliable marker exists that predicts the treatment outcome. In the present study, we investigated the apoptotic activation of caspases in HCV patients undergoing antiviral therapy with regard to the treatment outcome. We determined caspase activation in sera from patients who were either responding or nonresponding to antiviral therapy by using two novel caspase assays, an immunological and a luminometric enzyme test. We found that compared with nonresponding individuals, responding patients showed significantly (P < .05) increased caspase activity, which was closely correlated with virus elimination (r = 0.81). The cutoff value of serum caspase activity was determined, which correctly predicted the treatment outcome with a sensitivity of 70% and a specificity of 82% (area under the curve 0.845; 95% CI). In conclusion, hepatic caspase activity might play a role in HCV clearance and could also predict the efficacy of antiviral therapy.

Impact of obesity on treatment of chronic hepatitis C

Obesity and the metabolic syndrome have hepatic manifestations, including steatosis and progression of fibrosis. In individuals with chronic hepatitis C, obesity is associated with inflammation, insulin resistance, steatosis, progression of fibrosis, and nonresponse to treatment with interferon or peginterferon alpha and ribavirin. Patients with both hepatitis C and obesity-related nonalcoholic fatty liver disease are at greater risk for more advanced liver disease. We review the mechanisms by which obesity may be associated with decreased efficacy of interferon-based therapies in individuals with chronic hepatitis C and the therapeutic strategies that may increase the effectiveness of these therapies in obese individuals.