De-Immunizing foreign gene therapy for the nervous System: An optogenetics case study 4627

Abstract Description Foreign genes, such as microbial-derived optogenetic proteins, hold transformative potential for treating neurological disorders. However, immune response to these therapeutic transgenes compromises their long-term efficacy. This challenge is particularly pronounced in the peripheral nervous system (PNS), where neurons lack the protection of the blood-brain barrier (BBB). Here, we use non-mammalian opsin protein as a model system to show that sustained transgene expression can be achieved in the spinal cord by modifying the routes of administration. AAVs encoding channelrhodopsin-2 (ChR2) were injected through direct methods in C57BL/6J mice, and functional expression was assessed through transdermal optical stimulation of sciatic nerves. Immune response was evaluated via ELISA, histology, and epitope mapping to determine immunogenicity. Results We show that antigen presentation is dependent on delivery route. Direct injections in spinal cord resulted in robust and sustained ChR2 expression for more than a year, compared to rapid transgene loss (within 8-12 weeks) observed with intramuscular delivery. Functional assessments showed consistent opsin expression with reduced immune cell infiltration, low antibody titer, and higher Treg count. Conclusion This work demonstrates that foreign gene expression can be successfully sustained and tolerated, significantly expanding potential applications and paving the way for broader integration of gene therapies into the nervous system. Funding Sources Supported by Schmidt Science Fellows Award, Yang-Tan Centre for Bionics at MIT, HHMI and NIH R01DA029639. Topic Categories Neuroimmunology (NEUR)