Autophagy determines efficiency of liver-directed gene therapy with Adeno-associated viral vectors

Use of Adeno-associated viral (AAV) vectors for liver-directed gene therapy has shown considerable success, particularly in patients with severe hemophilia B. However, the high vector doses required to reach therapeutic levels of transgene expression caused liver inflammation in some patients that selectively destroyed transduced hepatocytes. We hypothesized that such detrimental immune responses can be avoided by enhancing the efficacy of AAV vectors in hepatocytes. Because autophagy is a key liver response to environmental stresses, we characterized the impact of hepatic autophagy on AAV infection. We found that AAV induced mammalian target of rapamycin (mTOR)-dependent autophagy in human hepatocytes. This cell response was crucially required for efficient transduction because under condition of impaired autophagy (pharmacological inhibition, siRNA knock-down of autophagic proteins or suppression by food intake), rAAV-mediated transgene expression was markedly reduced, both in vitro and in vivo. Taking advantage of this dependency, we employed pharmacological inducers of autophagy to increase the level of autophagy. This resulted in greatly improved transduction efficiency of AAV vectors in human and mouse hepatocytes independent of the transgene, driving promoter or AAV serotype, and was subsequently confirmed in vivo. Specifically, short-term treatment with a single dose of torin 1 significantly increased vector-mediated hepatic expression of erythropoietin in C57BL/6 mice. Similarly, co-administration of rapamycin with AAV vectors resulted in markedly enhanced expression of human acid-α-glucosidase in non-human primates. Conclusion: We identified autophagy as a pivotal cell response determining the efficiency of AAV's intracellular processing in hepatocytes and thus the outcome of liver-directed gene therapy using AAV vectors, and showed in a proof-of-principle study how this newly identified virus-host-interaction can be employed to enhance efficacy of this vector system. This article is protected by copyright. All rights reserved.

Publication year:2017

Keywords:A1 Journal article

BOF-keylabel:yes

BOF-publication weight:10

CSS-citation score:2

Authors:International

Authors from:Higher Education

Accessibility:Open