Engineering adeno-associated viral vectors to evade innate immune and inflammatory responses
Horae Gene Therapy Center; Li Weibo Institute for Rare Diseases Research; Department of Microbiology and Physiological Systems
Genetics and Genomics | Immunology and Infectious Disease | Therapeutics | Translational Medical Research
Nucleic acids are used in many therapeutic modalities, including gene therapy, but their ability to trigger host immune responses in vivo can lead to decreased safety and efficacy. In the case of adeno-associated viral (AAV) vectors, studies have shown that the genome of the vector activates Toll-like receptor 9 (TLR9), a pattern recognition receptor that senses foreign DNA. Here, we engineered AAV vectors to be intrinsically less immunogenic by incorporating short DNA oligonucleotides that antagonize TLR9 activation directly into the vector genome. The engineered vectors elicited markedly reduced innate immune and T cell responses and enhanced gene expression in clinically relevant mouse and pig models across different tissues, including liver, muscle, and retina. Subretinal administration of higher-dose AAV in pigs resulted in photoreceptor pathology with microglia and T cell infiltration. These adverse findings were avoided in the contralateral eyes of the same animals that were injected with the engineered vectors. However, intravitreal injection of higher-dose AAV in macaques, a more immunogenic route of administration, showed that the engineered vector delayed but did not prevent clinical uveitis, suggesting that other immune factors in addition to TLR9 may contribute to intraocular inflammation in this model. Our results demonstrate that linking specific immunomodulatory noncoding sequences to much longer therapeutic nucleic acids can "cloak" the vector from inducing unwanted immune responses in multiple, but not all, models. This "coupled immunomodulation" strategy may widen the therapeutic window for AAV therapies as well as other DNA-based gene transfer methods.
DOI of Published Version
Chan YK, Wang SK, Chu CJ, Copland DA, Letizia AJ, Costa Verdera H, Chiang JJ, Sethi M, Wang MK, Neidermyer WJ Jr, Chan Y, Lim ET, Graveline AR, Sanchez M, Boyd RF, Vihtelic TS, Inciong RGCO, Slain JM, Alphonse PJ, Xue Y, Robinson-McCarthy LR, Tam JM, Jabbar MH, Sahu B, Adeniran JF, Muhuri M, Tai PWL, Xie J, Krause TB, Vernet A, Pezone M, Xiao R, Liu T, Wang W, Kaplan HJ, Gao G, Dick AD, Mingozzi F, McCall MA, Cepko CL, Church GM. Engineering adeno-associated viral vectors to evade innate immune and inflammatory responses. Sci Transl Med. 2021 Feb 10;13(580):eabd3438. doi: 10.1126/scitranslmed.abd3438. PMID: 33568518. Link to article on publisher's site
Science translational medicine
Chan YK, Muhuri M, Tai PW, Xie J, Gao G, Church GM. (2021). Engineering adeno-associated viral vectors to evade innate immune and inflammatory responses. University of Massachusetts Medical School Faculty Publications. https://doi.org/10.1126/scitranslmed.abd3438. Retrieved from https://escholarship.umassmed.edu/faculty_pubs/2013