Sustained Correction of Motoneuron Histopathology Following Intramuscular Delivery of AAV in Pompe Mice

Abstract

Pompe disease is an autosomal recessive disorder caused by mutations in the acid-α glucosidase (GAA) gene. Lingual dysfunction is prominent but does not respond to conventional enzyme replacement therapy (ERT). Using Pompe (Gaa(-/-)) mice, we tested the hypothesis that intralingual delivery of viral vectors encoding GAA results in GAA expression and glycogen clearance in both tongue myofibers and hypoglossal (XII) motoneurons. An intralingual injection of an adeno-associated virus (AAV) vector encoding GAA (serotypes 1 or 9; 1 × 10(11) vector genomes, CMV promoter) was performed in 2-month-old Gaa(-/-) mice, and tissues were harvested 4 months later. Both serotypes robustly transduced tongue myofibers with histological confirmation of GAA expression (immunochemistry) and glycogen clearance (Period acid-Schiff stain). Both vectors also led to medullary transgene expression. GAA-positive motoneurons did not show the histopathologic features which are typical in Pompe disease and animal models. Intralingual injection with the AAV9 vector resulted in approximately threefold more GAA-positive XII motoneurons (P < 0.02 versus AAV1); the AAV9 group also gained more body weight over the course of the study (P < 0.05 versus AAV1 and sham). We conclude that intralingual injection of AAV1 or AAV9 drives persistent GAA expression in tongue myofibers and motoneurons, but AAV9 may more effectively target motoneurons.

Stimulation of Respiratory Motor Output and Ventilation in a Murine Model of Pompe Disease by Ampakines

“…1,3,7,18). Several independent groups have concluded that neuropathology has a significant impact on motor function (8,49,54), but no current therapies are aimed at improving the efferent neural regulation of the respiratory muscles (although a gene therapy clinical trial is in progress [55]).…”

“…In complementary studies, brainstem respiratory control neurons and motoneurons were histologically evaluated. Although motoneuron histopathology has been documented in Pompe tissues (1,4,7,18,19), currently, there is no information available regarding the impact of GAA gene deletion on the medullary neurons and networks that regulate breathing. This is a fundamental consideration, as delineation of the neuronal mechanisms contributing to respiratory failure in Pompe disease is a prerequisite for optimizing therapeutic strategies.…”

Copackaged AAV9 Vectors Promote Simultaneous Immune Tolerance and Phenotypic Correction of Pompe Disease

“…11,[42][43][44][45][46][47] In addition, we and others have described the capabilities of AAV-mediated expression of GAA to elicit detrimental immune responses against the transgene. 1,50,55 To address this complication for improved systemic outcomes, we pursued the use of a liver-specific promoter (apolipoprotein Ehepatocyte locus control region-human alpha-1 antitrypsin promoter [LSP]) to drive expression of human codon-optimized GAA (coGAA) for induction of GAA-specific T regs capable of dampening a systemic immune response against GAA.…”

“…10 Injection of AAV-GAA locally, regionally, or systemically has demonstrated greater potential to attenuate the pathology associated with Pompe disease compared with ERT. [42][43][44][45][46][47] These studies prompted the first clinical trial in Pompe disease patients with intradiaphragm injection of AAV1-GAA. 48,49 It is noteworthy that clinical management of the immune response was necessary during the course of this clinical trial to prevent antitransgene immunity as ERT was maintained for ethics considerations.…”

Profile of alglucosidase alfa in the treatment of Pompe disease: safety, efficacy, and patient acceptability

“…73 Promising future therapies also involve injection of recombinant adeno-associated virus vectors, as this therapy has been demonstrated to augment cardiac, respiratory, and motorneuron function in GAA −/− knockout mice. [74][75][76][77][78] Importantly, the degree of restoration once again seems to depend on the severity of disease. Therefore, an early therapy appears to be the most effective.…”