26 August 2024
Marchese M, et al. Neurobiol Dis. 2024 Jul;197:106536. ABSTRACT CLN8 is an endoplasmic reticulum cargo receptor and a regulator of lysosome biogenesis whose loss of function leads to neuronal ceroid lipofuscinosis. CLN8 has been linked to autophagy and lipid metabolism, but much remains to be learned, and there are no therapies acting on the molecular signatures in this disorder. The present study aims to characterize the molecular pathways involved in CLN8 disease and, by pinpointing altered ones, to identify potential therapies. To bridge the gap between cell and mammalian models, we generated a new zebrafish model of CLN8 deficiency, which recapitulates the pathological features of the disease. We observed, for the first time, that CLN8 dysfunction impairs autophagy. Using autophagy modulators, we showed that trehalose and SG2 are able to attenuate the pathological phenotype in mutant larvae, confirming autophagy impairment as a secondary event in disease progression. Overall, our successful modeling of CLN8 defects in zebrafish highlights this novel in vivo model's strong potential as an instrument for exploring the role of CLN8 dysfunction in cellular pathways, with a view to identifying small molecules to treat this rare disease. Access the article here [Targeting autophagy impairment improves the phenotype of a novel CLN8 zebrafish model - ScienceDirect]
Santos BV, et al. Neuropediatrics. 2024 Jun 10. Epub ahead of print. ABSTRACT Introduction: Neuronal ceroid lipofuscinoses (CLNs) are a group of lysosomal storage disorders of genetic origin, characterized by progressive neurodegeneration and intracellular accumulation of autofluorescent lipopigment. Thirteen genes related to CLNs are currently described, showing genetic and allelic heterogeneity, most of them with an autosomal recessive pattern. Due to the few descriptions of cases related to CLNs in Brazil, it is necessary to describe the phenotypic and genotypic characteristics of these patients. This study aims to evaluate the genotypic profile and correlate it with the phenotypic characteristics of patients with CLN in a children's hospital. Methods: This study was performed as a descriptive cross-sectional study with analysis of medical records, imaging, and laboratory tests of patients who had a confirmed molecular diagnosis of CLN. Results: The sample consisted of 11 patients from nine families with different subtypes of CLNs (CLN2, 5, 6, 7, and 8), with CLN2 being the most prevalent in the study. A total of 16 mutation variants were identified in genes associated with the five CLNs described in this study, with typical and atypical clinical phenotypes depending on the subtype and its variants. Conclusion: Novel mutations identified in the patients in this study showed phenotypes of rapid and severe progression in the CLN2 patient and similar characteristics in CLN6 and CLN7 patients, as previously described in the literature. Access the article here [Phenotypic/Genotypic Profile of Children with Neuronal Ceroid Lipofuscinosis in Southern Brazil - PubMed (nih.gov)]
He H, et al. Ann Neurol. 2024 Jun 15. Online ahead of print. ABSTRACT Objective: The aim of this study was to explore the pathogenesis of CLCN6-related disease and to assess whether its Cl-/H+-exchange activity is crucial for the biological role of ClC-6. Methods: We performed whole-exome sequencing on a girl with development delay, intractable epilepsy, behavioral abnormities, retinal dysfunction, progressive brain atrophy, suggestive of neuronal ceroid lipofuscinoses (NCLs). We generated and analyzed the first knock-in mouse model of a patient variant (p.E200A) and compared it with a Clcn6-/- mouse model. Additional functional tests were performed with heterologous expression of mutant ClC-6. Results: We identified a de novo heterozygous p.E200A variant in the proband. Expression of disease-causing ClC-6E200A or ClC-6Y553C mutants blocked autophagic flux and activated transcription factors EB (TFEB) and E3 (TFE3), leading to autophagic vesicle and cholesterol accumulation. Such alterations were absent with a transport-deficient ClC-6E267A mutant. Clcn6E200A/+ mice developed severe neurodegeneration with typical features of NCLs. Mutant ClC-6E200A, but not loss of ClC-6 in Clcn6-/- mice, increased lysosomal biogenesis by suppressing mTORC1-TFEB signaling, blocked autophagic flux through impairing lysosomal function, and increased apoptosis. Carbohydrate and lipid deposits accumulated in Clcn6E200A/+ brain, while only lipid storage was found in Clcn6-/- brain. Lysosome dysfunction, autophagy defects, and gliosis were early pathogenic events preceding neuron loss. Interpretation: CLCN6 is a novel genetic cause of NCLs, highlighting the importance of considering CLCN6 mutations in the diagnostic workup for molecularly undefined forms of NCLs. Uncoupling of Cl- transport from H+ countertransport in the E200A mutant has a dominant effect on the autophagic/lysosomal pathway. Access the article here [Mutations in CLCN6 as a Novel Genetic Cause of Neuronal Ceroid Lipofuscinosis - He - Annals of Neurology - Wiley Online Library]
Nakashima S, et al. Intern Med. 2024 Jun 15;63(12):1807-1812. ABSTRACT Neuronal ceroid lipofuscinosis type 2 (CLN2) is an autosomal recessive lysosomal disease caused by decreased activity of the enzyme tripeptidyl peptidase 1 (TPP1) due to pathogenic variants in the TPP1 gene. Cerliponase alfa, a recombinant proenzyme form of TPP1, has shown efficacy in preventing motor and language function decline in early-stage CLN2. However, the safety and effects of this therapy in advanced-stage CLN2 are unclear. We herein report a case of intraventricular cerliponase alfa treatment for over a year in a patient with advanced-stage CLN2. The results suggest the safety and potential efficacy of treatment at an advanced stage of CLN2. Access the article here [Intraventricular Cerliponase Alfa Treatment in a Patient with Advanced Neuronal Ceroid Lipofuscinosis Type 2 (jst.go.jp)]
Wünkhaus, D. et al. Sci Rep 14, 17469 (2024). ABSTRACT Mutations in the lysosomal membrane protein CLN3 cause Juvenile Neuronal Ceroid Lipofuscinosis (JNCL). Activation of the lysosomal ion channel TRPML1 has previously been shown to be beneficial in several neurodegenerative disease models. Here, we tested whether TRPML1 activation rescues disease-associated phenotypes in CLN3-deficient retinal pigment epithelial (ARPE-19 CLN3-KO) cells. ARPE-19 CLN3-KO cells accumulate LAMP1 positive organelles and show lysosomal storage of mitochondrial ATPase subunit C (SubC), globotriaosylceramide (Gb3), and glycerophosphodiesters (GPDs), whereas lysosomal bis(monoacylglycero)phosphate (BMP/LBPA) lipid levels were significantly decreased. Activation of TRPML1 reduced lysosomal storage of Gb3 and SubC but failed to restore BMP levels in CLN3-KO cells. TRPML1-mediated decrease of storage was TFEB-independent, and we identified TRPML1-mediated enhanced lysosomal exocytosis as a likely mechanism for clearing storage including GPDs. Therefore, ARPE-19 CLN3-KO cells represent a human cell model for CLN3 disease showing many of the described core lysosomal deficits, some of which can be improved using TRPML1 agonists. Access the article here [TRPML1 activation ameliorates lysosomal phenotypes in CLN3 deficient retinal pigment epithelial cells | Scientific Reports (nature.com)]
Fyke, Z. et al. Mol Genet Metab. 2024 Jul 15;143(1-2):108537. ABSTRACT Infantile neuronal ceroid lipofuscinosis (CLN1 Batten Disease) is a devastating pediatric lysosomal storage disease caused by pathogenic variants in the CLN1 gene, which encodes the depalmitoylation enzyme, palmitoyl-protein thioesterase 1 (PPT1). CLN1 patients present with visual deterioration, psychomotor dysfunction, and recurrent seizures until neurodegeneration results in death, typically before fifteen years of age. Histopathological features of CLN1 include aggregation of lysosomal autofluorescent storage material (AFSM), as well as profound gliosis. The current management of CLN1 is relegated to palliative care. Here, we examine the therapeutic potential of a small molecule PPT1 mimetic, N-tert-butyl hydroxylamine (NtBuHA), in a Cln1-/- mouse model. Treatment with NtBuHA reduced AFSM accumulation both in vitro and in vivo. Importantly, NtBuHA treatment in Cln1-/- mice reduced neuroinflammation, mitigated epileptic episodes, and normalized motor function. Live cell imaging of Cln1-/- primary cortical neurons treated with NtBuHA partially rescued aberrant synaptic calcium dynamics, suggesting a potential mechanism contributing to the therapeutic effects of NtBuHA in vivo. Taken together, our findings provide supporting evidence for NtBuHA as a potential treatment for CLN1 Batten Disease. Access the article [ here ]
Nicolaou, P. Front Genet. 2024 Jun 26:15:1430703. No Abstract available. Access the article [ here ]
Bellamy, KKL, et al. Anim Genet. 2024 Aug;55(4):612-620 ABSTRACT Neuronal ceroid lipofuscinosis (NCL) is a group of neurodegenerative disorders that occur in humans, dogs, and several other species. NCL is characterised clinically by progressive deterioration of cognitive and motor function, epileptic seizures, and visual impairment. Most forms present early in life and eventually lead to premature death. Typical pathological changes include neuronal accumulation of autofluorescent, periodic acid-Schiff- and Sudan black B-positive lipopigments, as well as marked loss of neurons in the central nervous system. Here, we describe a 19-month-old Schapendoes dog, where clinical signs were indicative of lysosomal storage disease, which was corroborated by pathological findings consistent with NCL. Whole genome sequencing of the affected dog and both parents, followed by variant calling and visual inspection of known NCL genes, identified a missense variant in CLN6 (c.386T>C). The variant is located in a highly conserved region of the gene and predicted to be harmful, which supports a causal relationship. The identification of this novel CLN6 variant enables pre-breeding DNA-testing to prevent future cases of NCL6 in the Schapendoes breed, and presents a potential natural model for NCL6 in humans. Access the article [ here ]
Mhlanga-Mutangadura, T. et al. Genes (Basel). 2024 May 23;15(6):661. ABSTRACT A 23-month-old neutered male dog of unknown ancestry presented with a history of progressive neurological signs that included anxiety, cognitive impairment, tremors, seizure activity, ataxia, and pronounced visual impairment. The clinical signs were accompanied by global brain atrophy. Due to progression in the severity of disease signs, the dog was euthanized at 26 months of age. An examination of the tissues collected at necropsy revealed dramatic intracellular accumulations of autofluorescent inclusions in the brain, retina, and cardiac muscle. The inclusions were immunopositive for subunit c of mitochondrial ATP synthase, and their ultrastructural appearances were similar to those of lysosomal storage bodies that accumulate in some neuronal ceroid lipofuscinosis (NCL) diseases. The dog also exhibited widespread neuroinflammation. Based on these findings, the dog was deemed likely to have suffered from a form of NCL. A whole genome sequence analysis of the proband's DNA revealed a homozygous C to T substitution that altered the intron 3-exon 4 splice site of CLN6. Other mutations in CLN6 cause NCL diseases in humans and animals, including dogs. The CLN6 protein was undetectable with immunolabeling in the tissues of the proband. Based on the clinical history, fluorescence and electron-microscopy, immunohistochemistry, and molecular genetic findings, the disorder in this dog was classified as an NCL resulting from the absence of the CLN6 protein. Screening the dog's genome for a panel of breed-specific polymorphisms indicated that its ancestry included numerous breeds, with no single breed predominating. This suggests that the CLN6 disease variant is likely to be present in other mixed-breed dogs and at least some ancestral breeds, although it is likely to be rare since other cases have not been reported to date. Access the article [ here ]
Huang WC, Ohnsman CM, et al. Invest Ophthalmol Vis Sci. 2024 Jul 1;65(8):45 ABSTRACT Purpose: Bilateral progressive, symmetrical loss of central retinal thickness (CRT) has been described in neuronal ceroid lipofuscinosis type 2 (CLN2) disease. This study details the pattern of morphological changes underlying CRT loss and disease progression in patients receiving intracerebroventricular (ICV) enzyme replacement therapy (ERT) with cerliponase alfa. Methods: Spectral-domain optical coherence tomography macular cube scans were collected from 16 patients with classic CLN2 disease receiving ICV ERT. Detailed retinal structure analyses were performed on manually segmented horizontal B-scans through the fovea to determine the thickness of six retinal parameters and the extent of ellipsoid zone (EZ) loss. Results: Anatomical changes primarily occurred in photoreceptor (PR)-related retinal parameters and correlated with ocular disease severity. Retinal degeneration began with initial focal parafoveal EZ discontinuities signaling the onset of rapid PR degeneration in a predictable pattern: parafoveal PR involvement with foveal sparing followed by profound parafoveal and foveal PR loss with additional thinning beyond the central retina. PR degeneration began with outer segment loss and progressed to outer nuclear layer (ONL) involvement. Longitudinal analyses confirmed these observations. The rate of PR loss was fastest at the fovea at ?58 mm per year and became slower at locations farther away from the fovea. Conclusions: Retinal degeneration in CLN2 disease is primarily associated with PR loss in a predictable pattern, with EZ disruption signaling early PR stress. CRT, ONL thickness, and PR layer thickness are useful anatomical biomarkers for understanding disease progression and treatment efficacy in CLN2. Studies using en face images will further clarify CLN2-related retinal degeneration. Access the article here [OCT Biomarkers in Ocular CLN2 Disease in Patients Treated With Intraventricular Enzyme Replacement Therapy - PMC (nih.gov)]
Breuillard D, et al. Eur J Neurol. 2024 Sep;31(9):e16324. PMID: 38693756 ABSTRACT Neuronal ceroid lipofuscinosis type 2 (CLN2) disease is a rare, lysosomal storage disorder that causes pediatric onset neurodegenerative disease. It is characterized by mutations in the TPP1 gene. Symptoms begin between 2 and 4?years of age with loss of previously acquired motor, cognitive, and language abilities. Cerliponase alfa, a recombinant human TPP1 enzyme, is the only approved therapy. We report the first presymptomatic cerliponase alfa intraventricular treatment in a familial case of CLN2 related to a classical TPP1 variant. Sister 1 presented with motor, cognitive, and language decline and progressive myoclonic epilepsy since the age of 3?years, evolved with severe diffuse encephalopathy, received no specific treatment, and died at 11?years. Sister 2 had a CLN2 presymptomatic diagnosis and has been treated with cerliponase since she was 12 months old. She is now 6?years 8?months and has no CLN2 symptom except one generalized seizure 1?year ago. No serious adverse event has occurred. Repeated Wechsler Preschool and Primary Scale of Intelligence, Fourth Edition standardized index scores are heterogeneous in the extremely low to low average ranges. Mean length of utterances, a global index of sentence complexity, showed a delay, but a gradual improvement. The reported case enhances the major contribution of presymptomatic diagnosis and significant middle?term treatment benefit for patients with CLN2. Access the article here [Ceroid lipofuscinosis type 2 disease: Effective presymptomatic therapy—Oldest case of a presymptomatic enzyme therapy - PMC (nih.gov)]