Capsid antigen presentation flags human hepatocytes for destruction after transduction by adeno-associated viral vectors.
Adeno-associated virus (AAV) vectors are effective gene delivery vehicles mediating long-lasting transgene expression. Data from a clinical trial of AAV2-mediated hepatic transfer of the Factor IX gene (F9) into hemophilia B subjects suggests that CTL responses against AAV capsid can eliminate transduced hepatocytes and prevent long-term F9 expression. However, the capacity of hepatocytes to present AAV capsid-derived antigens has not been formally demonstrated, nor whether transduction by AAV sensitizes hepatocytes for CTL-mediated destruction. To investigate the fate of capsids after transduction, we engineered a soluble TCR for the detection of capsid-derived peptide:MHC I (pMHC) complexes. TCR multimers exhibited antigen and HLA specificity and possessed high binding affinity for cognate pMHC complexes. With this reagent, capsid pMHC complexes were detectable by confocal microscopy following AAV-mediated transduction of human hepatocytes. Although antigen presentation was modest, it was sufficient to flag transduced cells for CTL-mediated lysis in an in vitro killing assay. Destruction of hepatocytes was inhibited by soluble TCR, demonstrating a possible application for this reagent in blocking undesirable CTL responses. Together, these studies provide a mechanism for the loss of transgene expression and transient elevations in aminotransferases following AAV-mediated hepatic gene transfer in humans and a potential therapeutic intervention to abrogate these limitations imposed by the host T cell response.
Division of Allergy and Immunology, Children's Hospital of Philadelphia and University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Gary C
GC
Pien
Etiena
E
Basner-Tschakarjan
Daniel J
DJ
Hui
Ashley N
AN
Mentlik
Jonathan D
JD
Finn
Nicole C
NC
Hasbrouck
Shangzhen
S
Zhou
Samuel L
SL
Murphy
Marcela V
MV
Maus
Federico
F
Mingozzi
Jordan S
JS
Orange
Katherine A
KA
High
D017951:Antigen Presentation / Q000276:immunology*; D036022:Capsid Proteins / Q000276:immunology* / Q000378:metabolism; D002460:Cell Line; D003602:Cytotoxicity, Immunologic / Q000276:immunology*; D000229:Dependovirus / Q000235:genetics*; D005822:Genetic Vectors / Q000235:genetics*; D022781:Hepatocytes / Q000166:cytology / Q000276:immunology* / Q000378:metabolism*; D006649:Histocompatibility Antigens / Q000276:immunology; D006801:Humans; D055503:Protein Multimerization; D011948:Receptors, Antigen, T-Cell / Q000276:immunology; D012995:Solubility; D013379:Substrate Specificity; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology
D036022:Capsid Proteins; D006649:Histocompatibility Antigens; D011948:Receptors, Antigen, T-Cell