Hepatitis C Virus - Dendritic Cell Interactions and DC Therapy
Research Team and Collaborators
- Project leader: Sylvia van den Hurk
- Scientists: Joyce Wilson, Qiang Liu
- Graduate students: Amir Landi, Ethel Athanli
Background:
Hepatitis C virus (HCV) is the etiological agent of non-A, non-B hepatitis and the only member of the Hepacivirus genus within the Flaviviridae family. An estimated 170 million people are currently infected worldwide, which amounts to 3.1% of the world population. Although acute infection is often insidious, only 15-25% of infected people clear the virus. The majority of patients remain chronic carriers. Persistent infection occurs despite the development of humoral and cellular immune responses against the structural proteins and eventually results in either mild chronic hepatitis or extensive liver damage, including fibrosis, cirrhosis, and hepatocellular carcinoma. The only effective therapy is (pegylated) IFN-α in combination with ribavirin. These therapies, however, are expensive and associated with severe side effects. Furthermore, only a fraction of patients with chronic hepatitis C meet the criteria for drug treatment, which is then curative in about half of the treated patients. Consequently, hepatitis C is the leading cause of liver transplantation in North America.
Dendritic cells (DCs) play a critical role in the induction of a primary immune response. Dendritic cell maturation and function are modulated by the microenvironment, which is different and not optimal in chronic hepatitis C patients in comparison to healthy humans. If as suggested by some reports, DCs in chronic hepatitis C patients are functionally impaired, a therapeutic DC vaccine might circumvent the suboptimal microenvironment and/or diminished DC function of these patients in vivo by giving necessary maturation stimuli ex vivo. If, conversely, DCs from HCV patients are functionally normal, as suggested by others, DC-based vaccines, which are highly effective inducers of both CD8+ T cells and CD4+ Th cells, are also expected to be promising as therapeutic for chronic hepatitis C patients and possibly as prophylactic for high-risk populations.
Objectives:
- Investigate effects of chronic HCV infection on the phenotype, function and gene expression profiles of human dendritic cells.
- Evaluate effects of co-infection with HCV and HIV on the phenotype, function and gene expression profiles of human dendritic cells.
- Optimize DC-based vaccination by ex vivo treatment of dendritic cells with immune modulators.
- Compare DC-based vaccines with DNA- and protein-based vaccines.
Progress:
One of our objectives is to use DC therapy against chronic hepatitis C infection. Since human monocyte-derived DCs are the most common source for DC therapy, it is critical to examine the effects of HCV gene products on monocytes. To address this issue, we developed an efficient non-viral transfection protocol for human monocyte-derived immature DCs (Mo-iDCs). The Mo-iDCs were then transfected with HCV mRNAs coding for HCV proteins, either individually or in combination. Overall, the HCV proteins did not impair these DCs functionally. In contrast, based on transcriptional, phenotypic and functional profiles, the Core protein appeared to effectively mature these iDCs, which is promising for DC therapy.
We have examined whether adoptive transfer of murine bone marrow DCs (BM-DCs) loaded with HCV NS3 protein, NS3/4A mRNA or NS5A mRNA ex vivo initiates HCV-specific immune responses and protection. In addition to monitoring the humoral and cellular immune responses by ELISA, ELISPOT and CTL assays, the migration of activated DCs from the injection site to the draining lymph nodes was monitored, and the quality of the CD4+ and CD8+ T cells was evaluated based on MHC-tetramers. Immunized and control mice were challenged with recombinant vaccinia virus expressing HCV proteins, and viral replication examined. These studies showed that adoptive transfer of murine BM-DCs loaded with HCV NS3 protein, NS3/4A mRNA or NS5A mRNA ex vivo initiated potent HCV-specific cytotoxic T lymphocyte (CTL) responses and protection from challenge with recombinant vaccinia virus expressing NS3/4A and/or NS5 in mice.
Future Direction:
In the immediate future we will focus on the characterization of the effects of chronic hepatitis C on DC functions, as well as optimizing DC vaccination strategies. Since co-infection of HCV and HIV is very common, leading to additional complications, we plan to also study the interactions between HCV and HIV at the level of immune cell function. Furthermore, we will compare the efficacy of DC-based vaccines with DNA- and protein-based vaccines. Based on the expectation that with the identification of the receptors for HCV, mouse models will be available in the near future, we intend to ultimately evaluate vaccination strategies in live HCV mouse models.
Finally, effective strategies for vaccination against HCV, in particular those that induce robust and long-lasting cell-mediated immunity, and potentially break tolerance, will be applied to additional chronic diseases.
Funding Partners:
Publications:
- Yu, H., Babiuk, L.A. and van Drunen Littel-van den Hurk, S. 2008. Strategies for loading dendritic cells with hepatitis C NS5a antigen and inducing protective immunity. J. Viral Hepatitis 15(6):459-470.
- Landi, A. Babiuk, L.A. and van Drunen Littel-van den Hurk, S. 2007. High transfection efficiency and viability of human dendritic cells after non-viral gene transfer. J. Leukocyte Biol. 82(4):849-60.
