title: Potential for cellular stress response to hepatic factor VIII expression from AAV vector.
abstract: Hemophilia A and B are coagulation disorders resulting from the loss of functional coagulation factor VIII (FVIII) or factor IX proteins, respectively. Gene therapy for hemophilia with adeno-associated virus vectors has shown efficacy in hemophilia B patients. Although hemophilia A patients are more prevalent, the development of therapeutic adeno-associated virus vectors has been impeded by the size of the F8 cDNA and impaired secretion of FVIII protein. Further, it has been reported that over-expression of the FVIII protein induces endoplasmic reticulum stress and activates the unfolded protein response pathway bothin vitroand in hepatocytesin vivo, presumably due to retention of misfolded FVIII protein within the endoplasmic reticulum. Engineering of the F8 transgene, including removal of the B domain (BDD-FVIII) and codon optimization, now allows for the generation of adeno-associated virus vectors capable of expressing therapeutic levels of FVIII. Here we sought to determine if the risks of inducing the unfolded protein response in murine hepatocytes extend to adeno-associated virus gene transfer. Although our data show a mild activation of unfolded protein response markers followingF8gene delivery at a certain vector dose in C57BL/6 mice, it was not augmented upon further elevated dosing, did not induce liver pathology or apoptosis, and did not impact FVIII immunogenicity.
authors.affiliation: Department of Pediatrics, University of Florida , Gainesville, Florida, USA.
authors.forename: Irene
authors.initials: I
authors.lastname: Zolotukhin
authors.affiliation: Department of Pediatrics, University of Florida , Gainesville, Florida, USA.
authors.forename: David M
authors.initials: DM
authors.lastname: Markusic
authors.affiliation: Department of Pediatrics, University of Florida , Gainesville, Florida, USA.
authors.forename: Brett
authors.initials: B
authors.lastname: Palaschak
authors.affiliation: Department of Pediatrics, University of Florida , Gainesville, Florida, USA.
authors.forename: Brad E
authors.initials: BE
authors.lastname: Hoffman
authors.affiliation: Department of Pediatrics, University of Florida , Gainesville, Florida, USA.
authors.forename: Meera A
authors.initials: MA
authors.lastname: Srikanthan
authors.affiliation: Department of Pediatrics, University of Florida , Gainesville, Florida, USA.
authors.forename: Roland W
authors.initials: RW
authors.lastname: Herzog