AAV9-mediated Expression of a Non-self Protein in Nonhuman Primate Central Nervous System Triggers Widespread Neuroinflammation Driven by Antigen-presenting Cell Transduction

Abstract

Many studies have demonstrated that adeno-associated virus serotype 9 (AAV9) transduces astrocytes and neurons when infused into rat or nonhuman primate (NHP) brain. We previously showed in rats that transduction of antigen-presenting cells (APC) by AAV9 encoding a foreign protein triggered a full neurotoxic immune response. Accordingly, we asked whether this phenomenon occurred in NHP. We performed parenchymal or intrathecal infusion of AAV9 encoding green fluorescent protein (GFP), a non-self protein derived from jellyfish, or human aromatic L-amino acid decarboxylase (hAADC), a self-protein, in separate NHP. Animals receiving AAV9-GFP into cisterna magna (CM) became ataxic, indicating cerebellar pathology, whereas AAV9-hAADC animals remained healthy. In transduced regions, AAV9-GFP elicited inflammation associated with early activation of astrocytic and microglial cells, along with upregulation of major histocompatibility complex class II (MHC-II) in glia. In addition, we found Purkinje neurons lacking calbindin after AAV9-GFP but not after AAV9-hAADC delivery. Our results demonstrate that AAV9-mediated expression of a foreign-protein, but not self-recognized protein, triggers complete immune responses in NHP regardless of the route of administration. Our results warrant caution when contemplating use of serotypes that can transduce APC if the transgene is not syngeneic with the host. This finding has the potential to complicate preclinical toxicology studies in which such vectors encoding human cDNA's are tested in animals.

Comparative Efficacy and Safety of Multiple Routes of Direct CNS Administration of Adeno-Associated Virus Gene Transfer Vector Serotype rh.10 Expressing the Human Arylsulfatase A cDNA to Nonhuman Primates

“…The FLAG-tagged ARSA protein is a tool for evaluating breadth of expression with potential immunological implications irrelevant to the candidate therapeutic. Foreign proteins such as green fluorescent protein have been shown to generate immune-mediated brain lesions in nonhuman primates similar to our findings, even if delivered by the noninvasive intracisternal route (Samaranch et al, 2014). Therefore, an immune reaction to the FLAG peptide appears to be a possible explanation for the lesions we observed.…”

“…These doses are 1-2 logs higher than that being tested in current human AAV gene therapy trials, and thus unlikely to be reasonable for translation to human use (High, 2012). As an alternative, the minimally invasive administration to cerebral spinal fluid via the cisterna magna reservoir in nonhuman primates has shown that intracisternal infusion of AAV vectors (i.e., AAV7 and AAV9) results in widespread cortical neuronal expression of transgenes (Gray, 2013;Bankiewicz, 2014;Samaranch et al, 2014). Because of limitations typical for nonhuman primate studies, we chose not to investigate the use of several AAV serotypes via multiple routes of administration, instead focusing on the one serotype, AAVrh.10.…”

“…Although it has been shown that AAV serotypes such as AAV9 can cross the blood-brain barrier and transduce brain parenchyma in rodents and nonhuman primates (Gray, 2013;Samaranch et al, 2014), intravenous applications are relatively inefficient, with most of the vector remaining in the viscera and unlikely to be efficacious for diffuse CNS disorders such as MLD. At the high vector dose necessary to achieve brain expression in adult mice ( >1.5 · 10 12 genome copies [GC]/kg) (Maguire et al, 2013), translation to human application will require massive levels of vector, with possible adverse effects.…”

Destination Brain: the Past, Present, and Future of Therapeutic Gene Delivery

“…Depending on the therapeutic strategy though, limited diffusion could be beneficial when a local effect is desired (Drinkut et al, 2012). Intrathecal delivery revealed promising results in rodents with spinal cord injury (SCI) (Milligan et al, 2006); however, it led to severe neurotoxic effects in monkeys (Samaranch et al, 2014). Overall, the route of administration must be tailored to the therapeutic usage, while reducing associated risks and optimizing ease of use and efficacy.…”

Transfer of optogenetic vectors into the brain of neonatal animals to study neuron functions during subsequent periods of development

“…С другой стороны, каналородопсин -чужеродный белок, встраивающийся в мембрану нейронов и экспонирующийся на их поверх-ности, что способно индуцировать развитие реакции микроглии и элиминацию этих клеток. Даже экспрессия внутриклеточного чужеродного белка, обеспеченная его доставкой в клетки мозга AAV2 вирусом, способна, хотя и в меньшей степени, чем доставка AAV9 вирусом, индуци-ровать элиминацию клеток, экспрессирующих этот белок (Samaranch et al, 2014). Оба предложенных механизма снижения экспрессии Н134 у животных 9-недельного возраста представляются вполне реальными, поскольку убедительно показаны на генетических конструкциях, по-добных нашей.…”