Characterization of neurological disease progression in a canine model of CLN5 neuronal ceroid lipofuscinosis

Abstract

Golden Retriever dogs with a frameshift variant in CLN5 (c.934_935delAG) suffer from a progressive neurodegenerative disorder analogous to the CLN5 form of neuronal ceroid lipofuscinosis (NCL). Five littermate puppies homozygous for the deletion allele were identified prior to the onset of disease signs. Studies were performed to characterize the onset and progression of the disease in these dogs. Neurological signs that included restlessness, unwillingness to cooperate with the handlers, and proprioceptive deficits first became apparent at approximately 12 months of age. The neurological signs progressed over time and by 21 to 23 months of age included general proprioceptive ataxia, menace response deficits, aggressive behaviors, cerebellar ataxia, intention tremors, decreased visual tracking, seizures, cognitive decline, and impaired prehension. Due to the severity of these signs, the dogs were euthanized between 21 and 23 months of age. Magnetic resonance imaging revealed pronounced progressive global brain atrophy with a more than sevenfold increase in the volume of the ventricular system between 9.5 and 22.5 months of age. Accompanying this atrophy were pronounced accumulations of autofluorescent inclusions throughout the brain and spinal cord. Ultrastructurally, the contents of these inclusions were found to consist primarily of membrane-like aggregates. Inclusions with similar fluorescence properties were present in cardiac muscle. Similar to other forms of NCL, the affected dogs had low plasma carnitine concentrations, suggesting impaired carnitine biosynthesis. These data on disease progression will be useful in future studies using the canine model for therapeutic intervention studies.

A Homozygous MAN2B1 Missense Mutation in a Doberman Pinscher Dog with Neurodegeneration, Cytoplasmic Vacuoles, Autofluorescent Storage Granules, and an α-Mannosidase Deficiency

“…Consistent with this possibility, the color of the fluorescence emission of the storage material was similar in sections of the cerebral cortex and spinal cord but shifted red in sections of the cerebellum. Similar variations between tissues in fluorescence emission color, as well as in storage body ultrastructure, are seen in the neuronal ceroid lipofuscinoses and similar lysosomal storage disorders [ 6 , 8 , 9 , 12 , 13 , 14 , 15 , 22 , 27 , 28 , 31 , 42 , 64 , 95 , 96 , 97 , 98 , 99 ]. For example, in dogs with the form of neuronal ceroid lipofuscinosis resulting from a mutation in ATP13A2 , the fluorescence emission color of storage bodies ranged from greenish–yellow to golden–yellow to orange–yellow in cells of different tissues, and there were tissue-specific differences in storage body ultrastructure [ 6 ].…”

“…The unstained sections were examined for autofluorescence as described previously [ 31 ]. Slices of both immuno-fixed and EM-fixed tissues were paraffin-embedded, and sections were either stained with hematoxylin and eosin (H&E) or immunostained for localization of glial fibrillary acidic protein (GFAP), ionized calcium-binding adapter molecule 1 (Iba1), and mitochondrial ATP synthase subunit c. Immunohistochemical staining was performed as described previously [ 8 , 31 , 41 , 42 ]. Slices of the EM-fixed cerebral cortex, cerebellar cortex, and cervical spinal cord were also processed for electron microscopy.…”

“…One or more mutations in 20 canine orthologs of human LSD genes have been reported to be likely causes of canine LSDs. These canine genes include ARSB , ATP13A2 , CLN5 , CLN6 , CLN8 , CTSD , GAA , GALC , GLB1 , GUSB , HEXA , HEXB , IDUA , MANBA , MFSD8 , NAGLU , PPT1 , SGSH , and TPP1 [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ]. In addition, mutations in ARSG and CNP have been reported to be likely causes of canine LSDs [ 30 , 31 ], although the human disorders associated with mutations in these genes have not yet been formally recognized as LSDs [ 32 , 33 , 34 , 35 , 36 ].…”

Characterization of neuropathology in ovine CLN5 and CLN6 neuronal ceroid lipofuscinoses (Batten disease)

“…model (Jolly et al, 1992), and dilated cerebellar sulci without gross degeneration are seen in MRI or computed tomography studies of canine Border collie, Australian cattle dog, and Golden retriever CLN5 (Koie et al, 2004;Kolicheski et al, 2016;Meiman et al, 2022;Mizukami et al, 2012). The reason why cerebellar pathology, aside from lysosomal storage and the late-stage white matter microgliosis detected here in sheep, does not often manifest in animal NCLs is unclear.…”

“…Naturally occurring CLN6 ( nclf ) mice exhibit progressive retinal atrophy, neurodegeneration, and premature death (Bronson et al., 1993; Mirza et al., 2013; Morgan et al., 2013), but the CLN5 exon 3 knockout mouse model lacks the severe brain (cortical and cerebellar) atrophy characteristic of the human disease (Kopra et al., 2004). Only mild cerebellar atrophy was reported for the Devon cattle CLN5 model (Jolly et al., 1992), and dilated cerebellar sulci without gross degeneration are seen in MRI or computed tomography studies of canine Border collie, Australian cattle dog, and Golden retriever CLN5 (Koie et al., 2004; Kolicheski et al., 2016; Meiman et al., 2022; Mizukami et al., 2012). The reason why cerebellar pathology, aside from lysosomal storage and the late‐stage white matter microgliosis detected here in sheep, does not often manifest in animal NCLs is unclear.…”