alpha-Glutathione S-transferase levels in chronic hepatitis C infection and the effect of alpha-interferon therapy

ASS and SULT2A1 are Novel and Sensitive Biomarkers of Acute Hepatic Injury-A Comparative Study in Animal Models

Liver and kidney damage associated with polytrauma, endotoxic shock/sepsis, and organ transplantation, are among the leading causes of the multiple organ failure. Development of novel sensitive biomarkers that detect early stages of liver and kidney injury is vital for the effective diagnostics and treatment of these life-threatening conditions. Previously, we identified several hepatic proteins, including Argininosuccinate Synthase (ASS) and sulfotransferases which were degraded in the liver and rapidly released into circulation during Ischemia/Reperfusion (I/R) injury. Here we compared sensitivity and specificity of the newly developed sandwich ELISA assays for ASS and the sulfotransferase isoform SULT2A1 with the standard clinical liver and kidney tests Alanine Aminotransferase (ALT) and Aspartate Transaminase (AST) in various pre-clinical models of acute injury. Our data suggest that ASS and SULT2A1 have superior characteristics for liver and kidney health assessment in endotoxemia, Ischemia/Reperfusion (I/R), chemical and drug-induced liver injury and may be of high potential value for clinical applications.

Liver iron accumulation in chronic hepatitis C patients without HFE mutations: relationships with histological damage, viral load and genotype and alpha-glutathione S-transferase levels

BACKGROUND

Host and viral factors have been suggested as possible causative factors for the presence of liver iron accumulation in chronic hepatitis C. However, there is no agreement regarding the influence of liver iron accumulation on the biochemical and histological severity of chronic hepatitis C. Moreover, data concerning the relationships between both viral load and genotype and liver iron accumulation are scanty.

AIMS

To evaluate the biochemical, histological and virological assessment of a group of chronic hepatitis C patients without risk factors for iron overload, on the basis of the presence, degree and distribution of liver iron accumulation.

METHODS

Fifty-three chronic hepatitis C patients (34 men, 19 women; age 44 +/- 11 years) with no risk factors for liver iron accumulation and showing no HFE mutations were chosen from a broader cohort of chronic hepatitis C patients. The presence, degree and distribution of liver iron accumulation were assessed using Deugnier's score. Relationships between the presence of liver iron accumulation and grading and staging were carried out separately. Hepatitis C virus RNA serum levels and viral genotype were compared in patients with or without liver iron accumulation. Alpha glutathione S-transferase serum levels were assessed in all patients.

RESULTS

Overall, liver iron accumulation was mild and was present in 19 patients (36%). It was associated with male gender (P = 0.0358), and was reflected by high serum iron levels (P = 0.001) and high ferritin levels (P < 0.0001). Hepatitis C virus RNA levels and genotype were not associated with the presence of liver iron accumulation. In multivariate analysis, ferritin was the only variable significantly associated with liver iron accumulation (P < 0.0001). Grading was higher in patients with liver iron accumulation regardless of the site of iron deposition. Fibrosis was present in all patients with iron overload; these patients were more frequently cirrhotic. Moreover, patients with mesenchymal or mixed deposition had higher staging than patients with hepatocytic or no iron deposition. This feature was reflected by higher alpha-glutathione S-transferase levels.

CONCLUSIONS

Liver iron accumulation is mild in chronic hepatitis C patients without HFE mutations and is mainly reflected by serum ferritin levels. Viral characteristics do not seem to play a role in iron deposition. Liver iron accumulation is associated with higher grading, advanced fibrosis and cirrhosis. Moreover, higher staging is associated with mesenchymal or mixed iron deposition. In these patients, higher alpha-glutathione S-transferase levels seem to reflect more complex damage.

Utility of alpha-glutathione S-transferase assessment in chronic hepatitis C patients with near normal alanine aminotransferase levels

OBJECTIVES

To study whether determining alpha-glutathione S-transferase (alpha-GST) might improve the assessment of chronic hepatitis C (CHC) patients with near normal alanine aminotransferase levels (NNA).

DESIGN AND METHODS

We studied 119 viraemic CHC patients. They were subdivided into two groups according to the pattern of alanine aminotransferase (ALT) alteration, i.e. consistently above (HA) or below (NNA) twice the upper normal value. In these patients we assessed alpha-GST and correlated its levels to clinical, histological, and virological findings, further evaluating whether alpha-GST might improve the assessment of CHC patients with NNA.

RESULTS

alpha-GST showed a significant correlation with aminotransferases, though not with histological necroinflammatory activity and fibrosis or with hepatitis C virus RNA levels. Twenty-seven patients had NNA (23%), and within this subgroup of patients alpha-GST identified a subset of patients with a higher viral load.

CONCLUSIONS

alpha-GST in CHC patients is related to hepatocellular necrosis parameters, but unrelated both to histology and to viraemia. However, in patients with NNA, alpha-GST identified a subgroup of patients with a higher viral load. In this subgroup of patients alpha-GST alteration likely represents the expression of a more severe damage. Because this injury is not detectable by the usual biochemical or histological work-up, we suggest that alpha-GST could a useful tool for monitoring liver damage over time.

Comparison between serum alpha-glutathione S-transferase and aminotransaminases in detecting cytolysis in hepatitis C-infected children

BACKGROUND

alpha-Glutathione S-transferase (alphaGST) has been proposed as a more sensitive indicator than serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in detecting hepatocellular damage due to chronic hepatitis C virus (HCV) infection.

METHODS

The accuracy of alpha-GST was compared with that of ALT and AST in detecting cytolysis in 103 blood samples issued from 31 children positive for HCV RNA.

RESULTS

alpha-GST had a lower sensitivity than ALT or AST (32% vs. 54.4% for each aminotransferase). The sensitivity of ALT and/or AST was 60.2%, whereas that of ALT and/or alpha-GST and AST and/or alpha-GST was lower (58.3% and 57.3%, respectively). Among 41 serum samples with negative ALT and AST, only 2 had positive alpha-GST, whereas alpha-GST failed to detect cytolysis in 31 samples with elevated ALT and/or AST. No correlation was found between alpha-GST, ALT, or AST and the Knodell score.

CONCLUSIONS

The combination of ALT with AST is actually the best compromise in detecting cytolysis in untreated HCV-infected patients.

Variability of Glutathione S-Transferase α in Human Liver and Plasma

Background: Glutathione S-transferases are a family of enzymes involved in the binding, transport, and detoxification of a wide variety of endogenous and exogenous compounds. Little information is available about the variability of class α glutathione S-transferases in human liver, where they are highly expressed, or in serum.

Methods: Both total class α glutathione S-transferase (GST-α, composed of GSTA1-1, GSTA1-2, and GSTA2-2) as well as GSTA1-1 concentrations were measured by specific and sensitive ELISA in liver cytosols of 35 organ donors and in plasma samples of 350 healthy controls.

Results: The mean total GST-α and GSTA1-1 in liver cytosols were 25.1 ± 9.4 and 10.7 ± 5.3 μg/mg protein, respectively, and did not correlate with activities of aspartate aminotransferase or alanine aminotransferase. The mean total GST-α in liver was significantly higher in females compared with males (28.8 ± 10.0 vs 22.0 ± 7.8 μg/mg protein; P &lt;0.05). In contrast, the median total GST-α in plasma was lower in females compared with males (2.0 and 2.8 μg/L, respectively; P &lt;0.0001). The median ratios for GSTA1-1/total GST-α in liver and plasma were 0.42 and 0.58, respectively.

Conclusions: GSTA1-1 constitutes approximately one-half of the total amount of α class GSTs in human plasma and liver. Total GST-α values are higher in female liver but lower in plasma compared with the respective values in males.

Determination of plasma alpha-glutathione S-transferases in patients with HCV-related chronic infection: its significance and possible clinical relevance

AIMS/BACKGROUND

Alpha-glutathione S-transferases (alpha-GST) are the cytoplasmatic class of enzymes responsible for cellular detoxifying processes. We evaluated the plasma alpha-GST activity in relation to chronic infection caused by hepatitis C virus (HCV).

METHODS

Eighteen anti-HCV-negative healthy subjects (controls), 32 anti-HCV-positive subjects with a constant normality of alanine aminotransferases (ALT) and gamma-glutamyl transpeptidase (gamma-GT) levels ("apparently healthy carriers"), and 85 patients with HCV-related chronic liver disease (40 chronic hepatitis, 27 cirrhosis, and 18 with hepatocellular carcinoma) were studied. We assayed plasma alpha-GST in all subjects upon their entry into the study; and every 6 months for 3 years in the control group and in anti-HCV apparently healthy carriers.

RESULTS

Alpha-GST values were significantly higher than normal values in 57% of the 21 HCV-RNA-positive apparently healthy carriers and in none of 11 persistently HCV-RNA-negative subjects; the highest increment of alpha-GST was documented in patients with chronic hepatitis. We did not observe correlation among HCV-RNA, histological activity, gamma-GT and ALT or alpha-GST values.

CONCLUSIONS

Therefore, the increment of plasma alpha-GST indicates a liver involvement even when ALT levels are normal. This may be clinically relevant to "apparently healthy carriers" whose plasma alpha-GST values, when increased, might need further evaluation.

Glutathione S-transferases as biomarkers of organ damage: applications of rodent and canine GST enzyme immunoassays

The cytosolic glutathione S-transferase (GST) enzymes serve as ideal biomarkers of organ damage as they exhibit many of the required characteristics, i.e. specific localisation, high cytosolic concentration and relatively short half-life. The role of GSTs as early indicators of organ damage is applicable to both human and animal models. Because of the regio-specific localisation of the different isoforms of GST in liver and kidney, simultaneous monitoring of classes of GSTs in biological matrices permits the identification of specific areas of damage within a particular organ. Immunoassays have been developed which quantify canine alpha GST and roden microGST (Yb1). The immunoassays are solid phase EIAs, where GST in the sample or standard is captured by a specific anti-GST antibody coated onto the solid phase. After washing, a specific enzyme-labelled IgG conjugate is added which binds to the captured GST. After a further washing step, substrate is added and a colour developed. The absorbance is measured on an ELISA plate reader and is directly proportional to the amount of GST present in the sample. The assays are performed at room temperature and can be completed within 3 h. The immunoassays are specific for each GST and have a range of 0-100 micrograms/l. A range of assay parameters were investigated to validate the EIAs for GST detection. The assays are sensitive and reproducible. CV for inter- and intra-assay variation were below 9% for Yb1 assay and below 20% for the canine alpha GST EIA. Recovery of spiked GST over the standard curve range was 102 and 99%, respectively. No prozone effect was observed and samples exhibited linearity of dilution in both assays. Validation has shown that using these enzyme immunoassay, Yb1 and canine alpha GST can be measured accurately and precisely in biological matrices, tissue homogenates and cell lines and that changes in GST levels can be detected. The use of these assays have important applications in both in vitro and in vivo toxicity studies, where GST's serve as sensitive marker of hepatocellular and renal cell integrity.

Alpha-glutathione transferases in HCV-related chronic hepatitis: a new predictive index of response to interferon therapy?

BACKGROUND/AIM

The aim of this study was to evaluate if plasma levels of alpha-glutathione-S-transferases (determined in basal conditions and monthly for 1 year during and 1 year after interferon therapy) could characterize patients who show only a primary response.

METHODS

We studied 48 patients with biopsy-proven, hepatitis C virus ribonucleic acid positive chronic hepatitis treated with interferon: 18 were "Sustained Responders", 12 "Relapsers" and 18 "Non-Responders".

RESULTS

Relapsers showed higher basal levels of alpha-glutathione-S-transferases, which remained higher than normal even when alanine aminotransferases normalized. No correlation was documented between alpha-glutathione-S-transferase levels and all other parameters examined (alanine aminotransferases, gamma-glutamyl-transpeptidase, viremia, and histological activity index).

CONCLUSIONS

These findings suggest that alpha-glutathione-S-transferase levels may be considered a predictive index of response to interferon therapy in chronic hepatitis C patients.