DNA damage/p53, innate immune, and unfolded protein responses are activated in primate liver after toxic, high-dose AAV-SMN1 delivery

Administration of high doses of a recombinant adeno-associated virus vector expressing the SMN1 protein (AAV-SMN1) can cause severe acute liver injury and death in non-human primates (NHPs) and, in rare cases, in patients. This study aimed to elucidate the molecular mechanisms underlying AAV-SMN1-induced liver damage. Transcriptomic analysis was performed using RNA-sequencing data from the livers of NHPs and rats receiving escalating doses of AAV-SMN1 and sacrificed 4-5 days later. Profound, dose-dependent transcriptomic changes were observed in NHPs. At the toxic, highest doses, there was significant upregulation of genes involved in the DNA damage/p53 response, pro-apoptotic unfolded protein response (UPR), and innate immune response, along with downregulation of genes associated with hepatocyte metabolic pathways. In contrast, NHPs receiving low doses and rats showed transcriptional changes indicative of antiviral pathway activation and T cell responses. In high-dose NHPs, SMN1 transgene levels correlated positively with pro-apoptotic UPR genes and inversely with hepatocyte identity genes. Here, we propose that AAV-induced hepatotoxicity involves cell-intrinsic mechanisms, such as UPR activation and the DNA damage/p53 response, which, along with the activation of innate immune responses, contribute to hepatocyte death. Targeting these pathways may offer a promising strategy for safer AAV-based therapies.