Low oxygen tension enhances hepatitis C virus replication.

Low oxygen tension exerts a significant effect on the replication of several DNA and RNA viruses in cultured cells. In vitro propagation of hepatitis C virus (HCV) has thus far been studied under atmospheric oxygen levels despite the fact that the liver tissue microenvironment is hypoxic. In this study, we investigated the efficiency of HCV production in actively dividing or differentiating human hepatoma cells cultured under low or atmospheric oxygen tensions. By using both HCV replicons and infection-based assays, low oxygen was found to enhance HCV RNA replication whereas virus entry and RNA translation were not affected. Hypoxia signaling pathway-focused DNA microarray and real-time quantitative reverse transcription-PCR (qRT-PCR) analyses revealed an upregulation of genes related to hypoxic stress, glycolytic metabolism, cell growth, and proliferation when cells were kept under low (3% [vol/vol]) oxygen tension, likely reflecting cell adaptation to anaerobic conditions. Interestingly, hypoxia-mediated enhancement of HCV replication correlated directly with the increase in anaerobic glycolysis and creatine kinase B (CKB) activity that leads to elevated ATP production. Surprisingly, activation of hypoxia-inducible factor alpha (HIF-α) was not involved in the elevation of HCV replication. Instead, a number of oncogenes known to be associated with glycolysis were upregulated and evidence that these oncogenes contribute to hypoxia-mediated enhancement of HCV replication was obtained. Finally, in liver biopsy specimens of HCV-infected patients, the levels of hypoxia and anaerobic metabolism markers correlated with HCV RNA levels. These results provide new insights into the impact of oxygen tension on the intricate HCV-host cell interaction.

Evaluation of alternative serum biomarkers to monitor the progression of chronic HBV and HCV infection.

Chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infections are among the most serious health conditions affecting about 600 million people worldwide leading to a number of severe liver diseases. Due to the lack of warning signs or mild symptoms during the early stage of the infection, a molecular signature associated with disease progression would be useful. Based on our recent paper where candidate biomarkers were determined through topological and modularity analysis of protein interaction networks (PINs), this study was focused on the evaluation of MIF, TNFRSF1A, FAS and TMSB4X as diagnostic biomarkers in chronic HBV and HCV infections. The aim was to establish a molecular profile, by combining those markers, that would discriminate the different stages during the progression of chronic hepatitis. One hundred and fifteen patients infected with HBV or HCV categorized into three groups: non-cirrhotic, cirrhotic and with HCC, and 20 healthy subjects were enrolled in this study. Serum levels of the aforementioned factors were measured by ELISA. TNFRSF1A serum levels appeared statistically significantly increased in all patient groups compared to control group with a p-value of <0.05. Furthermore, the combination of TNFRSF1A and TMSB4X serum levels successfully classified 63, 47% of patients indicating an association with HBV and HCV infections. Thus, variations of serum levels of TNFRSF1A and TMSB4X could be associated with the different stages of the disease and may be utilized for further research. On the other hand, we found no contribution of MIF and FAS serum levels for successful classification of patients.

Propylthiouracil-induced hypothyroidism is associated with increased tolerance of the isolated rat heart to ischaemia-reperfusion.

The present study investigated the response of the hypothyroid heart to ischaemia-reperfusion. Hypothyroidism was induced in Wistar rats by oral administration of propylthiouracil (0.05%) for 3 weeks (HYPO rats), while normal animals (NORM) served as controls. Isolated hearts from NORM and HYPO animals were perfused in Langendorff mode and subjected to zero-flow global ischaemia followed by reperfusion (I/R). Post-ischaemic recovery of left ventricular developed pressure was expressed as % of the initial value (LVDP%). Basal expression of protein kinase C epsilon (PKCepsilon) and PKCdelta and phosphorylation of p46 and p54 c-jun NH(2)-terminal kinases (JNKs) in response to I/R were assessed by Western blotting. LVDP% was found to be significantly higher in HYPO hearts than in NORM. At baseline, PKCepsilon expression was 1.4-fold more in HYPO than in NORM hearts, P<0.05, while PKCdelta was not changed. Furthermore, basal phospho-p54 and -p46 JNK levels were 2.2- and 2.6-fold more in HYPO than in NORM hearts, P<0.05. In response to I/R, in NORM hearts, phospho-p54 and -p46 JNK levels were 5.5- and 6.0-fold more as compared with the baseline values, P<0.05, while they were not significantly altered in HYPO hearts. HYPO hearts seem to display a phenotype of cardioprotection against ischaemia-reperfusion and this is associated with basal PKCepsilon overexpression and attenuated JNK activation after I/R.