Liver expression of proteins controlling interferon-mediated signalling as predictive factors in the response to therapy in patients with hepatitis C virus infection.

Combination therapy with interferon-alpha (IFNalpha) and ribavirin is the current treatment of choice for hepatitis C virus (HCV) infection. However, an important number of patients fail to respond to this therapeutic strategy. Factors determining IFN responsiveness are not well understood, and assessment of biomarkers that predict the response to IFN therapy in HCV patients is necessary. Several studies show that particular HCV proteins are able to block IFN function through interaction with important IFN-signal mediators, such as signal transducers and activators of transcription (STATs). We performed immunostaining analysis of STATs in liver tissue from IFN-responder vs. non-responder HCV patients in order to compare the expression profile of these proteins between both groups. Tissue arrays of liver biopsies were used to study the expression of STAT1, STAT2, STAT5 and PIAS1 (protein inhibitor of activated STAT1). Robust and higher expression levels of STAT1, STAT2 and STAT5 in liver tissue from HCV patients were found when compared with samples from healthy donors. However, no significant differences were observed between IFN-responder and -non-responder groups, but rather increasing levels of STAT1, STAT2 and STAT5 paralleled the degree of liver injury. Importantly, PIAS1 expression in the nucleus of most hepatocytes in HCV tissue biopsy sections, particularly of non-responder HCV patients, strongly indicated a regulatory effect on STAT1-DNA binding, likely affecting the IFN late signalling. In conclusion, our evidence indicates that intense PIAS1 nuclear staining, widely distributed in hepatocytes of infected livers, could be a good predictive factor of a defective response to IFN treatment, and a biomarker that is easily detectable by immunostaining during standard histopathological liver biopsy analysis.

Bautista D ，Bermúdez-Silva FJ ，Lasarte JJ ，Rodriguez-Fonseca F ，Baixeras E ... -  《JOURNAL OF PATHOLOGY》

Predictive value of the phosphorylation of signal transducers and activators of transcription in the outcome of interferon therapy for chronic hepatitis C.

Signal transducers and activators of transcription (STATs) play a critical role in antiviral defense. To better understand pegylated interferon (IFN)-alpha and ribavirin combination therapy resistance, we examined the STAT expression in the liver. We immunostained Phospho-STAT1 (P-STAT1) and Phospho-STAT3 (P-STAT3) in 59 hepatitis C virus (HCV)-infected liver tissues and compared the expression of these STATs proteins and the clinicopathological factors. The number of P-STAT1 observed correlated significantly with the body mass index (BMI; p = 0.03) and homeostatic model assessment (p = 0.007). The number of P-STAT3 observed correlated significantly with the ALT level (p = 0.002) and platelet count (p = 0.002). The number of P-STAT1 nuclei in the sustained virological response (SVR) group was significantly larger than in the non-SVR group (p = 0.003). On multivariance analysis, the number of P-STAT1 nuclei (p = 0.004) and age (p = 0.016) were significant predictors of SVR. P-STAT1 in the liver tissue prior to IFN therapy correlated with an increased BMI and increased insulin resistance, and might be a useful predictor of HCV clearance by IFN therapy. On the other hand, P-STAT3 might play a critical role in the hepatocellular response against inflammatory damage.

Miyaaki H ，Ichikawa T ，Nakao K ，Takeshita S ，Shibata H ，Ozawa E ，Akiyama M ，Miuma S ，Eguchi K ... -  《-》

Altered expression and activation of signal transducers and activators of transcription (STATs) in hepatitis C virus infection: in vivo and in vitro studies.

Larrea E ，Aldabe R ，Molano E ，Fernandez-Rodriguez CM ，Ametzazurra A ，Civeira MP ，Prieto J ... -  《-》

Hepatic metallothionein in patients with chronic hepatitis C: relationship with severity of liver disease and response to treatment.

Carrera G ，Paternain JL ，Carrere N ，Folch J ，Courtade-Saïdi M ，Orfila C ，Vinel JP ，Alric L ，Pipy B ... -  《AMERICAN JOURNAL OF GASTROENTEROLOGY》

Expression of hepatitis C virus core protein inhibits interferon-induced nuclear import of STATs.

IFN-alpha combined with ribavirin is used for the treatment of chronic hepatitis C. However, HCV has mechanisms to resist the antiviral actions of IFN-alpha. In order to study the molecular mechanisms of this resistance, the effect of HCV gene expression on IFN-induced nuclear import of STAT transcription factors and the expression of antiviral MxA protein were studied. In transiently transfected hepatoma cells, HCV core and NS5A proteins clearly inhibited the nuclear import of STAT1 and MxA protein expression (core only), whereas other viral proteins had only a marginal effect. To confirm these observations, human osteosarcoma-derived cell lines, which inducibly express HCV core protein, the entire structural region (core-E1-E2-p7), the NS3-4A complex, NS4B, NS5A, or NS5B proteins were also used. IFN-induced nuclear accumulation of STAT1 was almost completely and STAT2 was partially blocked in cell lines expressing high levels of HCV core protein. Subsequently, in these cells, IFN-alpha-induced MxB protein expression was decreased. Tumor necrosis factor-alpha (TNF-alpha)-induced nuclear import of NF-kappaB was only weakly or not at all inhibited, suggesting that the nuclear import machinery in general was not impaired. The results demonstrate a novel mechanism by which HCV gene expression may interfere with IFN-mediated host defence systems.

Melén K ，Fagerlund R ，Nyqvist M ，Keskinen P ，Julkunen I ... -  《JOURNAL OF MEDICAL VIROLOGY》