title: The Balance between CD8+T Cell-Mediated Clearance of AAV-Encoded Antigen in the Liver and Tolerance Is Dependent on the Vector Dose.
abstract: The liver continuously receives antigens from circulation and the gastrointestinal tract. A complex immune regulatory system has evolved in order to both limit inflammation and promote tolerance in the liver. Although in situ immune tolerance mechanisms enable successful gene therapy and liver transplantation, at the same time they facilitate chronic infections by pathogens such as hepatitis viruses. It is, however, poorly understood why hepatocytes infected with hepatitis viruses or transduced with adeno-associated virus (AAV)-based vectors may be rejected by CD8+T cells several months later. We found that hepatic transfer of limited doses of an AAV-ovalbumin vector rapidly induced antigen-specific CD8+T cells that only became functionally competent after >2 months. At this time, CD8+T cells had downregulated negative checkpoint markers, e.g., the programmed death 1 [PD-1] receptor, and upregulated expression of relevant cytokines. At further reduced vector dose, only intrahepatic rather than systemic CD8+T cell responses occurred, showing identical delay in antigen clearance. In contrast, PD-1-deficient mice rapidly cleared ovalbumin. Interestingly, higher vector dose directed sustained transgene expression without CD8+T cell responses. Regulatory T cells, IL-10 expression, and Fas-L contributed to high-dose tolerance. Thus, viral vector doses profoundly impact CD8+T cell responses.
authors.affiliation: Department of Pediatrics, College of Medicine, University of Florida, Gainesville, FL 32610, USA.
authors.forename: Sandeep R P
authors.initials: SRP
authors.lastname: Kumar
authors.affiliation: Department of Pediatrics, College of Medicine, University of Florida, Gainesville, FL 32610, USA.
authors.forename: Brad E
authors.initials: BE
authors.lastname: Hoffman
authors.affiliation: Division of Immunology, Harvard Medical Center, Boston, MA 02115, USA.
authors.forename: Cox
authors.initials: C
authors.lastname: Terhorst
authors.affiliation: Division of Gastroenterology and Hepatology, Weill Cornell Medicine, New York, NY 10021, USA.
authors.forename: Ype P
authors.initials: YP
authors.lastname: de Jong
authors.affiliation: Department of Pediatrics, College of Medicine, University of Florida, Gainesville, FL 32610, USA. Electronic address: rherzog@ufl.edu.
authors.forename: Roland W
authors.initials: RW
authors.lastname: Herzog
mesh_terms: D000818:Animals; D000956:Antigens, Viral / Q000235:genetics / Q000276:immunology*; D060890:B7-H1 Antigen / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D000229:Dependovirus / Q000145:classification / Q000235:genetics / Q000276:immunology*; D015870:Gene Expression; D018014:Gene Transfer Techniques; D005822:Genetic Vectors / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D007108:Immune Tolerance; D008099:Liver / Q000276:immunology*; D008297:Male; D008568:Memory; D051379:Mice; D010641:Phenotype; D061026:Programmed Cell Death 1 Receptor / Q000378:metabolism; D015398:Signal Transduction; D037182:T-Cell Antigen Receptor Specificity; D014161:Transduction, Genetic
chemical_list: D000956:Antigens, Viral; D060890:B7-H1 Antigen; D016207:Cytokines; D061026:Programmed Cell Death 1 Receptor
keywords: CD8(+) T cell; adeno-associated virus; gene therapy; hepatitis; liver; tolerance