Hepatitis C Virus Proteins Inhibit C3 Complement Production Budhaditya Mazumdar a , Hangeun Kim a , Keith Meyer a , Sandip K. Bose a , b , Adrian M. Di Bisceglie a , Ratna B. Ray c and Ranjit Ray a , b a Departments of Internal Medicine b Molecular Microbiology and Immunology c Pathology, Saint Louis University, Saint Louis, Missouri, USA ABSTRACT The third component of human complement (C3) plays a central role in innate immune function as its activation is required to trigger classical as well as alternative complement pathways. In this study, we have observed that sera from patients chronically infected with hepatitis C virus (HCV) displayed significantly lower C3 levels than sera from healthy individuals. Liver biopsy specimens from the same patients also exhibited lower C3 mRNA expression than liver tissues from healthy donors. C3 mRNA level was reduced in hepatocytes upon infection with cell culture-grown HCV genotype 1a or 2a in vitro . Further analysis suggested that HCV core protein displayed a weak repression of C3 promoter activity by downregulating the transcription factor farnesoid X receptor (FXR). On the other hand, HCV NS5A protein strongly downregulated C3 promoter activity at the basal level or in the presence of interleukin-1β (IL-1β) as an inducer. In addition, the expression of the transcription factor CAAT/enhancer binding protein beta (C/EBP-β), which binds to the IL-1/IL-6 response element in the C3 promoter, was inhibited in liver biopsy specimens. Furthermore, expression of C/EBP-β was reduced in hepatocytes infected with cell culture-grown HCV, as well as in hepatocytes transfected with the NS5A genomic region of HCV. Together, these results underscore the role of HCV NS5A protein in impairing innate immune function.
Hepatitis C Virus Proteins Inhibit C3 Complement Production
Abstract
Hepatitis C Virus Proteins Inhibit C3 Complement Production Budhaditya Mazumdar a , Hangeun Kim a , Keith Meyer a , Sandip K. Bose a , b , Adrian M. Di Bisceglie a , Ratna B. Ray c and Ranjit Ray a , b a Departments of Internal Medicine b Molecular Microbiology and Immunology c Pathology, Saint Louis University, Saint Louis, Missouri, USA ABSTRACT The third component of human complement (C3) plays a central role in innate immune function as its activation is required to trigger classical as well as alternative complement pathways. In this study, we have observed that sera from patients chronically infected with hepatitis C virus (HCV) displayed significantly lower C3 levels than sera from healthy individuals. Liver biopsy specimens from the same patients also exhibited lower C3 mRNA expression than liver tissues from healthy donors. C3 mRNA level was reduced in hepatocytes upon infection with cell culture-grown HCV genotype 1a or 2a in vitro . Further analysis suggested that HCV core protein displayed a weak repression of C3 promoter activity by downregulating the transcription factor farnesoid X receptor (FXR). On the other hand, HCV NS5A protein strongly downregulated C3 promoter activity at the basal level or in the presence of interleukin-1β (IL-1β) as an inducer. In addition, the expression of the transcription factor CAAT/enhancer binding protein beta (C/EBP-β), which binds to the IL-1/IL-6 response element in the C3 promoter, was inhibited in liver biopsy specimens. Furthermore, expression of C/EBP-β was reduced in hepatocytes infected with cell culture-grown HCV, as well as in hepatocytes transfected with the NS5A genomic region of HCV. Together, these results underscore the role of HCV NS5A protein in impairing innate immune function.Preview Only. This article cannot be rented because we do not currently have permission from the publisher.
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Hepatitis C Virus Proteins Inhibit C3 Complement Production
Mazumdar, Budhaditya; Kim, Hangeun; Meyer, Keith; Bose, Sandip K.; Di Bisceglie, Adrian M.; Ray, Ratna B.; Ray, Ranjit
Follow Journal of Virology
, Volume 86 (4): 2221
American Society For Microbiology – Feb 15, 2012
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