910. AAV8-Mediated Expression of Glucocerebrosidase Ameliorates the Storage Pathology in the D409V/null Gaucher Mouse

Abstract

Gaucher disease is the most common of the >40 described lysosomal storage disorders. The primary manifestation of Gaucher disease is the accumulation of glucosylceramide (GL-1), predominantly in the macrophages of liver and spleen, due to a genetic defect in the lysosomal hydrolase glucocerebrosidase (GC). A mouse model of Type I Gaucher disease (D409V/null) was used to assess the efficacy of AAV8-mediated gene therapy. This mouse model exhibits only 5% of normal GC activity in visceral tissues resulting in elevated GL-1 levels and the appearance of enlarged macrophages (Gaucher cells) in liver, lung, and spleen at 3 months of age. The AAV vector (AAV8/DC172-hGC) used for these studies contained a hepatocyte-restricted promoter, DC172 (human 1-microglobulin enhancer, human 1-anti-trypsin promoter), to drive the expression of human GC. Intravenous administration of 31011 drp of AAV8/DC172-hGC into 4-week old D409V/null mice (prior to development of disease pathology) generated high levels of GC in the liver and serum, and subsequent uptake by the spleen and lung. Expression was sustained for the duration of the study (6 months) and was effective at preventing both the accumulation of GL-1 in the tissues and the consequent onset of Gaucher disease symptoms. A subsequent study in older mice (4-month old) with established disease pathology showed that administration of a similar dose of AAV8/DC172-hGC was also effective at reversing GL-1 storage in the affected tissues. Furthermore, AAV-treated mice were largely devoid of the lipid-engorged macrophages that were frequently observed in vehicle-treated D409V/null mice. A dose-response study, in which 5-month old mice received 31011, 11011 or 31010 drp of AAV8/DC172-hGC, yielded high and sustained expression of GC in all treatment groups. Three months post-injection, both the 31011 and 11011 drp dosed mice demonstrated a dramatic reduction in GL-1 levels and the number of Gaucher storage cells in liver, lung and spleen. Treatment also corrected the abnormal pathology, cell differentials and MIP-1 levels in the lungs of the D409V/null mice in a dose-dependent manner. Additionally, no antibodies to GC were detected, in accordance with previous AAV gene therapy studies using hepatocyte-restricted promoters. These data demonstrate the effectiveness of AAV-mediated gene therapy at preventing and correcting the biochemical and pathological abnormalities in the mouse model and thus support its continued development in the treatment of Gaucher Disease.