Hepatitis C virus (HCV) infection causes

Hepatitis C virus (HCV) frequently causes chronic liver disease. The cause of viral persistence might be an inappropriate type I interferon (IFN) induction. To analyze the host's IFN response in chronic hepatitis C, we measured the transcription level of type I IFN genes as well as type I IFN-regulated genes in liver tissue and corresponding blood samples from patients with chronic hepatitis C, nonviral liver diseases, and a suspected but later excluded liver disease. Competitive and real-time RT-PCR assays were used to quantify the messenger RNA (mRNA) levels of all known IFN-a, IFN-b, and IFN-k genes and those of some IFN-regulated genes. We failed to detect any hepatic type I IFN mRNA induction, although liver tissue of chronic hepatitis C patients contained high numbers of some type I IFN-inducible effector mRNA molecules. Analysis of peripheral blood samples, however, showed a clear type I IFN induction. Parallel experiments employing HCV replicon cell lines revealed that replication of HCV RNA is not sufficient to induce any type I IFN nor to induce directly type I IFN-regulated genes such as MxA. In conclusion, our data provide evidence for the absence of an induction of type I IFN genes by HCV in the human liver and argue for a further development of type I IFN-based therapies.

Adrenoleukodystrophy (ALD), an X-linked inherited metabolic disorder, is the most frequent inborn peroxisomal disease. It leads to demyelination in the central and peripheral nervous system. Defective beta-oxidation of saturated very long chain fatty acids (VLCFAs; C22:0-C26:0) in peroxisomes has been shown to lead to an accumulation of VLCFAs in leukoid areas of the central nervous system, peripheral nerves, adrenal gland, and blood. The ALD gene has been recently identified and encodes a 745-amino-acid protein. We screened patients with adrenoleukodystrophy/adrenomyeloneuropathy (ALD/AMN) from 20 kindreds for mutations in the ALD gene. Eleven missense and two nonsense mutations, five deletions, and one insertion were detected by direct sequencing of eight reverse transcribed fragments of the ALD-gene mRNA. Four mutations could be shown to be de novo. All mutations could be confirmed in carriers by sequencing genomic DNA. No correlation between the type of mutation and the severity of the phenotype could be observed. The mutations were not detected in the ALD gene of 30 healthy persons.

The treatment of choice for patients infected chronically with HCV is the combination of IFN-alpha and ribavirin. Monotherapy with ribavirin leads to a clinical and histological improvement, but its exact mechanism of action is unknown. Therefore, the effect of ribavirin on synthesis of inflammatory cytokines and on apoptosis in stimulated peripheral blood mononuclear cells (PBMCs) was investigated. PBMCs were isolated from the blood of HCV infected patients and from healthy volunteers. The effect of ribavirin on IFN-gamma and IL-1beta release in the supernatant of unstimulated and phytohemagglutinin (PHA) stimulated PBMCs was investigated by enzyme linked immunosorbent assay (ELISA). The effect on total DNA, RNA, and protein synthesis was analyzed by measurement of 3H-thymidine, 3H-uridine and 3H-leucine incorporation into cellular macromolecules. Ribavirin led to a dose-dependent decrease of the IFN-gamma but an increase of IL-1beta release into the supernatant of PHA-stimulated PBMCs. At the same time, a dose-dependent decrease of total DNA, RNA, and protein synthesis in cultures of PHA-stimulated PBMCs was demonstrated. These effects could be compensated by the addition of equimolar amounts of guanosine. The rate of apoptotic CD45+ and CD14+ cells in PBMCs cultures increased in a dose-dependent manner. Our data suggest that ribavirin administration to chronically HCV-infected patients could lead to a decrease of the synthesis of proinflammatory cytokines (e.g., IFN-gamma) by an inhibition of total DNA-, RNA-, and protein-synthesis and by induction of apoptosis in the cells of the inflammatory infiltrate. Furthermore, ribavirin could influence the synthesis of viral particles in the hepatocytes.

Subject headings hepatitis C like viruses; hepatitis C, chronic; RNA, viral/blood; virus replication; monocytes; interferon alpha/therapeutic use; polymerase chain reaction Abstract AIM To analyze the association of HCV-RNA with peripheral blood mononuclear cells (PBMC) and to answer the question whether HCV-RNA positivity in PBMC is due to viral replication. METHODS HCV-RNA was monitored in serum and PBMC preparations from 15 patients with chronic HCV infection before, during and after an IFN-α α α α α therapy using a nested RT/PCR technique. In a second approach, PBMC from healthy donors were incubated in HCV positive plasma. RESULTS In the IFN-α α α α α responding patients, HCV-RNA disappeared first from total RNA preparations of PBMC and then from serum. In contrast, in relapsing patients, HCV-RNA reappeared first in serum and then in PBMC. A quantitative analysis of the HCV-RNA concentration in serum was performed before and after transition from detectable to non detectable HCV-RNA in PBMC-RNA and vice versa. When HCV-RNA was detectable in PBMC preparations, the HCV concentration in serum was significantly higher than the serum HCV-RNA concentration when HCV-RNA in PBMC was not detectable. Furthermore, at no time during the observation period was HCV specific RNA observed in PBMC, if HCV-RNA in serum was under the detection limit. Incubation of PBMC from healthy donors with several dilutions of HCV positive plasma for two hours showed a concentration dependent PCR positivity for HCV-RNA in reisolated PBMC. CONCLUSION The detectability of HCV-RNA in total RNA from PBMC seems to depend on the HCV concentration in serum. Contamination or passive adsorption by circulating virus could be the reason for detection of HCV-RNA in PBMC preparations of chronically infected patients.