👤 Denia Ramirez-Montealegre

Juvenile neuronal ceroid lipofuscinosis (JNCL; CLN3 disease; Batten disease) is an autosomal recessive neurodegenerative disease of childhood. Symptoms typically present at school age with vision loss followed by progressive cognitive decline, motor dysfunction, seizures, and behavior problems. Studies on sex differences in JNCL have yielded mixed results, but parent anecdotes suggest that females experience a more precipitous disease course. Therefore, we sought to determine if sex-based differences exist in JNCL. We used data from the Unified Batten Disease Rating Scale (UBDRS), the Batten Disease Support and Research Association (BDSRA) database, and the PedsQL quality of life (QoL) survey to evaluate sex-based differences in functional independence and time from symptom onset to death. On average, females had JNCL symptom onset one year later and death one year earlier than did males. Despite a later age at onset, females had lower functional capability, earlier loss of independent function, and lower physical QoL. Future research in sex differences in JNCL may help to further understand the biological mechanisms underpinning the disease course and may point to targeted therapies. Show less

To use the Unified Batten Disease Rating Scale (UBDRS) to measure the rate of decline in physical and functional capability domains in patients with juvenile neuronal ceroid lipofuscinosis (JNCL) or Batten disease, a neurodegenerative lysosomal storage disorder. We have evaluated the UBDRS in subjects with JNCL since 2002; during that time, the scale has been refined to improve reliability and validity. Now that therapies are being proposed to prevent, slow, or reverse the course of JNCL, the UBDRS will play an important role in quantitatively assessing clinical outcomes in research trials. We administered the UBDRS to 82 subjects with JNCL genetically confirmed by CLN3 mutational analysis. Forty-four subjects were seen for more than one annual visit. From these data, the rate of physical impairment over time was quantified using multivariate linear regression and repeated-measures analysis. The UBDRS Physical Impairment subscale shows worsening over time that proceeds at a quantifiable linear rate in the years following initial onset of clinical symptoms. This deterioration correlates with functional capability and is not influenced by CLN3 genotype. The UBDRS is a reliable and valid instrument that measures clinical progression in JNCL. Our data support the use of the UBDRS to quantify the rate of progression of physical impairment in subjects with JNCL in clinical trials. Show less

Autoantibodies to brain proteins are present in Juvenile Neuronal Ceroid Lipofuscinosis (Batten disease) patients and in the Cln3-/- mouse model of this disease, suggesting an autoimmune component to pathogenesis. Using genetic or pharmaceutical approaches to attenuate this immune response in Cln3-/- mice, we demonstrate decreased neuroinflammation, decreased deposition of immunoglobulin G in the brain and protection of vulnerable neuron populations. Moreover, immune suppression results in a significant improvement in motor performance providing for the first plausible therapeutic approach for juvenile Batten disease. Show less

Juvenile neuronal ceroid lipofuscinoses (JNCL) or juvenile Batten disease is a recessively inherited childhood neurodegenerative disorder resulting from a mutation in CLN3, which encodes a putative lysosomal protein of unknown function. Recent evidence suggests that a disruption in CLN3 function results in altered regulation of arginine transport into lysosomes, and may influence intracellular arginine levels. We sought to investigate the possible consequences of arginine dysregulation in the brain of the Cln3(-/-) mouse model of JNCL. Using a combination of enzyme assays, metabolite profiling, quantitative reverse-transcription polymerase chain reaction and Western blotting, we analysed the activities and expression of enzymes involved in arginine metabolism in the cerebral cortex and cerebellum of Cln3(-/-) mice over several developmental time points. We report subtle, but significant changes in the activities of enzymes involved in the citrulline-NO recycling pathway, and altered regulation of neuronal nitric oxide synthase in the cortex and cerebellum of Cln3(-/-) mice. In addition, a significant decrease in arginine transport into cerebellar granule cells was observed, despite an apparent upregulation of the cationic amino acid transporter-1 transporter at the cell surface. Our results provide further evidence that CLN3 function and arginine homeostasis are intricately related, and that cellular mechanisms may act to compensate for the loss of this protein. This and other studies indicate that CLN3 dysfunction in JNCL may result in multiple disturbances in metabolism that together contribute to the pathophysiological processes underlying this disease. Show less

Batten disease, or juvenile neuronal ceroid lipofuscinosis (JNCL), results from mutations in the CLN3 gene. This disorder presents clinically around the age of 5 years with visual deficits progressing to include seizures, cognitive impairment, motor deterioration, hallucinations, and premature death by the third to fourth decade of life. The motor deficits include coordination and gait abnormalities, myoclonic jerks, inability to initiate movements, and spasticity. Previous work from our laboratory has identified an early reduction in catechol-O-methyltransferase (COMT), an enzyme responsible for the efficient degradation of dopamine. Alterations in the kinetics of dopamine metabolism could cause the accumulation of undegraded or unsequestered dopamine leading to the formation of toxic dopamine intermediates. We report an imbalance in the catabolism of dopamine in 3 month Cln3(-/-) mice persisting through 9 months of age that may be causal to oxidative damage within the striatum at 9 months of age. Combined with the previously reported inflammatory changes and loss of post-synaptic D1alpha receptors, this could facilitate cell loss in striatal projection regions and underlie a general locomotion deficit that becomes apparent at 12 months of age in Cln3(-/-) mice. This study provides evidence for early changes in the kinetics of COMT in the Cln3(-/-) mouse striatum, affecting the turnover of dopamine, likely leading to neuron loss and motor deficits. These data provide novel insights into the basis of motor deficits in JNCL and how alterations in dopamine catabolism may result in oxidative damage and localized neuronal loss in this disorder. Show less

Autoantibodies to glutamic acid decarboxylase (GAD65) have been reported in sera from the Cln3(-/-) mouse model of juvenile neuronal ceroid lipofuscinosis (JNCL), and in individuals with this fatal paediatric neurodegenerative disorder. To investigate the existence of other circulating autoreactive antibodies, we used sera from patients with JNCL and other forms of neuronal ceroid lipofuscinosis (NCL) as primary antisera to stain rat and human central nervous system sections. JNCL sera displayed characteristic patterns of IgG, but not IgA, IgE or IgM immunoreactivity that was distinct from the other forms of NCL. Immunoreactivity of JNCL sera was not confined to GAD65-positive (GABAergic) neurons, but also stained multiple other cell populations. Preadsorption of JNCL sera with recombinant GAD65 reduced the intensity of the immunoreactivity, but did not significantly change its staining pattern. Moreover, sera from Stiff Person Syndrome and Type I Diabetes, disorders in which GAD65 autoantibodies are present, stained with profiles that were markedly different from JNCL sera. Collectively, these studies provide evidence of the presence of autoreactive antibodies within multiple forms of NCL, and are not exclusively directed towards GAD65. Show less

Mutations in the CLN3 gene, which encodes a lysosomal membrane protein, are responsible for the neurodegenerative disorder juvenile Batten disease. A previous study on the yeast homolog to CLN3, designated Btn1p, revealed a potential role for CLN3 in the transport of arginine into the yeast vacuole, the equivalent organelle to the mammalian lysosome. Lysosomes isolated from lymphoblast cell lines, established from individuals with juvenile Batten disease-bearing mutations in CLN3, but not age-matched controls, demonstrate defective transport of arginine. Furthermore, we show that there is a depletion of arginine in cells derived from individuals with juvenile Batten disease. We have, therefore, characterized lysosomal arginine transport in normal lysosomes and show that it is ATP-, v-ATPase- and cationic-dependent. This and previous studies have shown that both arginine and lysine are transported by the same transport system, designated system c. However, we report that lysosomes isolated from juvenile Batten disease lymphoblasts are only defective for arginine transport. These results suggest that the CLN3 defect in juvenile Batten disease may affect how intracellular levels of arginine are regulated or distributed throughout the cell. This assertion is supported by two other experimental approaches. First, an antibody to CLN3 can block lysosomal arginine transport and second, expression of CLN3 in JNCL cells using a lentiviral vector can restore lysosomal arginine transport. CLN3 may have a role in regulating intracellular levels of arginine possibly through control of the transport of this amino acid into lysosomes. Show less

The pathogenic mechanisms underlying Batten disease are unclear. Patients uniformly possess autoantibodies against glutamic acid decarboxylase (GAD) that are predominantly reactive with a region of GAD (amino acids 1 to 20) distinct from subjects with autoimmune type 1 diabetes or stiff-person syndrome. Batten patients did not possess autoantibodies against other type 1 diabetes-associated autoantigens and human leukocyte antigen genotypes revealed no specific associations with this disease. Show less

Batten disease is an autosomal recessive disorder also known as juvenile neuronal ceroid lipofuscinosis. The most common mutation for this disease is an approximately 1-kbp deletion in the CLN3 gene, which accounts for about 80 to 85% of the mutation load. We developed a rapid assay for this mutation using the PCR to produce amplicons that are detected by nucleobase quenching of the fluorescent signal from a probe labeled with a fluorescent dye. The probe overlaps the deletion breakpoint and is completely base paired to the mutant amplicon. However, three bases at the 5' end of the probe do not base pair with the wild-type amplicon. The alleles are distinguished by the different melting temperatures of the probe amplicon hybrids. Comparison of this new method with an allele-specific PCR and gel electrophoresis-based method showed 100% concordance in determination of the genotype for 30 specimens (11 homozygous mutant, 8 heterozygotes, and 11 homozygous normal). PCR followed by allele-specific melting curve analysis using nucleobase quenching has utility as a rapid method for detection of the most common mutation that causes Batten disease. Show less

In Saccharomyces cerevisiae, transport of arginine into the vacuole has previously been shown to be facilitated by a putative H+/arginine antiport. We confirm that transport of arginine into isolated yeast vacuoles requires ATP and we demonstrate a requirement for a functional vacuolar H+-ATPase. We previously reported that deletion of BTN1 (btn1-delta), an ortholog of the human Batten disease gene CLN3, resulted in a decrease in vacuolar pH during early growth. We report that this altered vacuolar pH in btn1-delta strains underlies a lack of arginine transport into the vacuole, which results in a depletion of endogenous vacuolar arginine levels. This arginine transport defect in btn1-delta is complemented by expression of either BTN1 or the human CLN3 gene and strongly suggests a function for transport of, or regulation of the transport of, basic amino acids into the vacuole or lysosome for yeast Btn1p, and human CLN3 protein, respectively. We propose that defective transport at the lysosomal membrane caused by an absence of functional CLN3 is the primary biochemical defect that results in Batten disease. Show less