Huntington's Disease (HD) is a progressive neurodegenerative disease caused by a mutation in the huntingtin gene. The mutation leads to a toxic gain of function of the mutant huntingtin (mHtt)... Show moreHuntington's Disease (HD) is a progressive neurodegenerative disease caused by a mutation in the huntingtin gene. The mutation leads to a toxic gain of function of the mutant huntingtin (mHtt) protein resulting in cellular malfunction, aberrant huntingtin aggregation and eventually neuronal cell death. Patients with HD show impaired motor functions and cognitive decline. Elevated levels of glucocorticoids have been found in HD patients and in HD mouse models, and there is a positive correlation between increased glucocorticoid levels and the progression of HD. Therefore, antagonism of the glucocorticoid receptor (GR) may be an interesting strategy for the treatment of HD. In this study, we evaluated the efficacy of the selective GR antagonist CORT113176 in the commonly used R6/2 mouse model. In male mice, CORT113176 treatment significantly delayed the loss of grip strength, the development of hindlimb clasping, gait abnormalities, and the occurrence of epileptic seizures. CORT113176 treatment delayed loss of DARPP-32 immunoreactivity in the dorsolateral striatum. It also restored HD -related parameters including astrocyte markers in both the dorsolateral striatum and the hippocampus, and microglia markers in the hippocampus. This suggests that CORT113176 has both cell -type and brain regionspecific effects. CORT113176 delayed the formation of mHtt aggregates in the striatum and the hippocampus. In female mice, we did not observe major effects of CORT113176 treatment on HD -related symptoms, with the exception of the anti -epileptic effects. We conclude that CORT113176 effectively delays several key symptoms related to the HD phenotype in male R6/2 mice and believe that GR antagonism may be a possible treatment option. Show less
Winter, F. de; Quijorna, I.F.; Burnside, E.; Hobo, B.; Eggers, R.; Hoyng, S.A.; ... ; Verhaagen, J. 2022
Gene therapy is a powerful approach to promote spinal cord regeneration. For a clinical application it is important to restrict therapeutic gene expression to the appropriate time window to limit... Show moreGene therapy is a powerful approach to promote spinal cord regeneration. For a clinical application it is important to restrict therapeutic gene expression to the appropriate time window to limit unwanted side effects. The doxycycline (dox)-inducible system is a widely used regulatable gene expression platform, however, this system depends on a bacterial-derived immunogenic transactivator. The foreign origin of this transactivator prevents reliable regulation of therapeutic gene expression and currently limits clinical translation. The glycine-alanine repeat (GAR) of Epstein-Barr virus nuclear antigen-1 protein inhibits its presentation to cytotoxic T cells, allowing virus-infected cells to evade the host immune system. We developed a chimeric transactivator (GARrtTA) and show that GARrtTA has an immune-evading advantage over "classical" rtTA in vivo. Direct comparison of lentiviral vectors expressing rtTA and GARrtTA in the rat spinal cord shows that the GARrtTA system is inducible for 6 doxycycline-cycles over a 47 week period, whereas with the rtTA-based system luciferase reporter expression declines during the 3rd cycle and is no longer re-inducible, indicating that GARrtTA provides an immune-advantage over rtTA. Immunohistochemistry revealed that GARrtTA expressing cells in the spinal cord appear healthier and survive better than rtTA expressing cells. Characterization of the immune response shows that expression of GARrtTA, in contrast to rtTA, does not recruit cytotoxic T-cells to the transduced spinal cord. This study demonstrates that fusion of the GAR domain to rtTA results in a functional doxycycline-inducible transactivator with a clear immune-advantage over the classical rtTA in vivo. Show less
Eggers, R.; Winter, F. de; Arkenaar, C.; Tannemaat, M.R.; Verhaagen, J. 2019
