Deimmunization for gene therapy: host matching of synthetic zinc finger constructs enables long-term mutant Huntingtin repression in mice

Title	Deimmunization for gene therapy: host matching of synthetic zinc finger constructs enables long-term mutant Huntingtin repression in mice
Authors	Carmen Agustín-Pavón, Michal Mielcarek, Mireia Garriga-Canut, Mark Isalan
Magazine	Molecular Neurodegeneration
Date	09/06/2016
DOI	10.1186/s13024-016-0128-x
Introduction	Synthetic zinc finger (ZF) proteins are engineered to target specific DNA sequences, offering a promising approach for gene therapy. Our previous research introduced a ZF transcription repressor, ZF-KOX1, that binds to the expanded CAG-repeats within the Huntington's disease (HD) gene, HTT, effectively reducing mutant expression and delaying neurological symptoms in a mouse HD model for up to 3 weeks. This study aims to extend the duration of gene therapy effects through a single brain injection. Recognising the potential immune response to foreign proteins, we developed a host-matched ZF-KOX1 analogue, mZF-KRAB, for safer mouse treatment alongside rAAV vector delivery. We also evaluated the neuron-specific enolase promoter (pNSE) for its capacity to maintain long-term transgene expression, hoping to sustain HTT repression for up to 6 months post-injection. Findings revealed significant inflammatory responses and moderate neuronal loss when using non-host-matched ZF-KOX1 or GFP, whereas mZF-KRAB avoided these issues. Despite a pCAG promoter-induced decline in ZF expression by 6 weeks, the use of a neuron-specific enolase promoter maintained up to 77% repression of mutant HTT in the whole brain 3 weeks post-injection, with repression effects persisting at 48% and 23% at 12 and 24 weeks, respectively. These results suggest the potential for longer-term treatments with host-adapted ZF-AAV constructs, showing reduced toxicity and improved ZF protein expression and gene repression.
Quote	Carmen Agustín-Pavón, Michal Mielcarek and Mireia Garriga-Canut et al. Deimmunization for gene therapy: host matching of synthetic zinc finger constructs enables long-term mutant Huntingtin repression in mice. Mol Neurodegener. 2016. Vol. 11(1). DOI: 10.1186/s13024-016-0128-x
Materials	Biomaterials
Industry	Pharmaceutical Industry