Exogenous Galactosylceramide as Potential Treatment for CLN3 Disease

Abstract

Objective: CLN3 disease is the commonest of the neuronal ceroid lipofuscinoses, a group of pediatric neurodegenerative disorders. Functions of the CLN3 protein include antiapoptotic properties and facilitating anterograde transport of galactosylceramide from Golgi to lipid rafts. This study confirms the beneficial effects of long-term exogenous galactosylceramide supplementation on longevity, neurobehavioral parameters, neuronal cell counts, astrogliosis, and diminution in brain and serum ceramide levels in Cln3 Δex7/8 knock-in mice. Additionally, the impact of galactosylceramide on ceramide synthesis enzymes is documented. Methods: A group of 72 mice received galactosylceramide or vehicle for 40 weeks. The effect of galactosylceramide supplementation on Cln3 Δex7/8 mice was determined by performing behavioral tests, measuring ceramide in brains and serum, and assessing impact on longevity, subunit C storage, astrogliosis, and neuronal cell counts. Results: Galactosylceramide resulted in enhanced grip strength of forelimbs in male and female mice, better balance on the accelerating rotarod in females, and improved motor coordination during pole climbing in male mice. Brain and serum ceramide levels as well as apoptosis rates were lower in galactosylceramide-treated Cln3 Δex7/8 mice. Galactosylceramide also increased neuronal cell counts significantly in male and female mice and tended to decrease subunit C storage in specific brain regions. Astrogliosis dropped in females compared to a slight increase in males after galactosylceramide. Galactosylceramide increased the lifespan of affected mice. Interpretation: Galactosylceramide improved behavioral, neuropathological, and biochemical parameters in Cln3 Δex7/8 mice, paving the way for effective therapy for CLN3 disease and use of serum ceramide as a potential biomarker to track impact of therapies.

Exogenous Flupirtine as Potential Treatment for CLN3 Disease

“…The hyperactive phenotype prominent in vehicle-treated Cln3 Δex7/8 mice is described for the first time here in mice at of 18 weeks of age. This was not previously documented in Cln3 Δex7/8 mice at 40 weeks of age [ 28 ]. This suggests that, at a young age, Cln3 Δex7/8 mice express a distinct behavioral phenotype prior to onset of more severe CLN3 disease symptoms, including motor decline.…”

“…This variation among sexes is not a new observation in this disease. We documented this in another study using exogenous galactosylceramide as potential treatment for CLN3 disease [ 28 ].…”

“…The neuronal nuclear protein (NeuN) is a marker not detected in glial cells or other cells in the brain [ 28 ]. NeuN assesses neuronal health and loss of this protein is indicative of damage.…”

Sex differences in gene expression with galactosylceramide treatment in Cln3Δex7/8 mice

“…The therapeutic approach in this study consisted of treating Cln3 Δex7/8 mice with daily injections of GalCer over 40 weeks. GalCer supplementation resulted in promising outcomes improving some neurobehavioral aspects of the disease, increasing longevity of male and female mice, in addition to reducing ceramide levels in homozygous Cln3 Δex7/8 mouse brain from males and females [23].…”

“…A short-term study of injecting GalCer in homozygous Cln3 Δex7/8 mice for a period of 17 weeks resulted in significant improvements in the course of CLN3 disease including reduced ceramide levels, subunit C accumulation and gliosis in specific brain regions. This led to a prolonged trial of 40 weeks with exogenous GalCer that demonstrated beneficial effects on neurobehavioral and biochemical parameters, and increase in longevity of homozygous Cln3 Δex7/8 mice [23].…”