Batista, A. R. | bioRxiv Science

bioRxiv2025

AAV gene therapy for Cockayne syndrome

Cockayne Syndrome (CS) is an autosomal recessive, progressive developmental and neurodegenerative disease. Approximately 30% of cases are caused by mutations in the ERCC8/CSA gene. Patients with CS present with cutaneous photosensitivity, growth failure, shorter life span and a progressive degeneration of the central nervous system. Loss of function mutations in CSA result in deficiencies in transcription-coupled nucleotide excision repair, regulation of RNA Pol II mediated transcription repair of oxidative DNA damage, and mitochondrial metabolism. Currently there are no available therapies for these patients. AAV gene therapy offers an opportunity to address this unmet need. We designed a new AAV vector encoding human CSA under a CBA promoter. We tested the therapeutic efficacy of this AAV9-CSA vector by neonatal ICV injection in the Csa-/-;Xpa-/- mouse model. Treatment with AAV9-CSA resulted in a significant increase in lifespan, and broad distribution of human CSA in the brain and heart. Despite clear therapeutic benefit, we also observed neuroradiological abnormalities, neuropathologic alterations including hypo-myelination, astrocytosis, microgliosis, and likely life limiting transcriptomic alterations in liver at endpoint. Nonetheless, the success of these experiments paves the way for the first in human clinical translation of a gene therapy for CS patients.

neuroscience↗

bioRxiv2025

Intrastriatal delivery of a zinc finger protein targeting the mutant HTT gene obviates lipid phenotypes in zQ175DN HD mice

Reducing the burden of mutant Huntingtin (mHTT) protein in brain cells is a strategy for treating Huntingtons disease (HD). However, it is still unclear what pathological changes can be reproducibly reversed by mHTT lowering and whether these changes can be measured in peripheral biofluids. We previously found that lipid changes that occur in brain with HD progression could be prevented by attenuating HTT transcription of the mutant allele in a genetic mouse model (LacQ140) with inducible whole body lowering. Here, we tested whether intrastriatal injection of a therapeutic capable of repressing the mutant HTT allele with expanded CAG can provide similar protection against lipid changes in HD mice with a deletion of neo cassette (zQ175DN). Wild-type or zQ175DN mice were injected with AAV9 bearing a cDNA for a zinc finger protein (ZFP) which preferentially targets mutant HTT (ZFP-HTT) to repress transcription (1). Proteins from brain tissues were analyzed using western blot, capillary electrophoresis, and nitrocellulose filtration methods. Lipid analyses of brain tissue and plasma collected from the same mice were conducted by liquid chromatography and mass spectrometry (LC-MS). Somatic instability (SI) index was assessed using capillary gel electrophoresis of PCR products and was shown to be impeded by HTT-ZFP. Lowering mHTT levels by 43% for 4 months prevented loss of total lipid content including subclasses sphingomyelin (SM), ceramide, phosphatidylethanolamine (PE) and others of caudate-putamen in zQ175DN mice. Moreover, LC-MS analysis of plasma demonstrated total lipid increases and lipid changes in monogalactosyl monoacylglyceride (MGMG) and certain phosphatidylcholine (PC) species were reversed with the therapy. In summary, our data demonstrate that analyzing lipid signatures of brain tissue and peripheral biofluids are valuable approaches for evaluating potential therapies in a preclinical model of HD. FundingCHDI Foundation, Dake Family Fund Disclosure statementThe authors have nothing to disclose. Author contributionsAI and KS extracted lipids and performed computational and statistical analysis; AB and CS collected plasma and brain tissues; SL and ES performed protein chemistry; KC maintained mouse colonies, RM performed stereotaxic injections, RB subcloned ZFP cDNAs and prepared virus, MSE, NA, MD, and KKG planned experiments and wrote manuscript.

neuroscience↗