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Aberrant cholesterol homeostasis is implicated in the pathogenesis of amyotrophic lateral sclerosis (ALS), a fatal neuromuscular disease that is due to motor neuron (MN) death. Cellular toxicity from excess cholesterol is averted when it is enzymatically oxidized to oxysterols and bile acids (BAs) to promote its removal. In contrast, the auto oxidation of excess cholesterol is often detrimental to cellular survival. Although oxidized metabolites of cholesterol are altered in the blood and CSF of ALS patients, it is unknown if increased cholesterol oxidation occurs in the SC during ALS, and if exposure to oxidized cholesterol metabolites affects human MN viability. Here, we show that in the SOD1G93A mouse model of ALS that several oxysterols, BAs and auto oxidized sterols are increased in the lumbar SC, plasma, and feces during disease. Similar changes in cholesterol oxidation were found in the cervical SC of sporadic ALS patients. Notably, auto-oxidized sterols, but not oxysterols and BAs, were toxic to iPSC derived human MNs. Thus, increased cholesterol oxidation is a manifestation of ALS and non-regulated sterol oxidation likely contributes to MN death. Developing therapeutic approaches to restore cholesterol homeostasis in the SC may lead to a treatment for ALS.

Amyotrophic lateral sclerosis (ALS) is a fatal neuromuscular disease characterized by motor neuron (MN) death. Lipid dysregulation manifests during disease; however, it is unclear whether lipid homeostasis is adversely affected in the in the spinal cord gray matter (GM), and if so, whether it is because of an aberrant increase in lipid synthesis. Moreover, it is unknown whether lipid dysregulation contributes to MN death. Here, we show that cholesterol ester (CE) and triacylglycerol levels are elevated several-fold in the spinal cord GM of male sporadic ALS patients. Interestingly, HMG-CoA reductase, the rate-limiting enzyme in cholesterol synthesis, was reduced in the spinal cord GM of ALS patients. Increased cytosolic phospholipase A2 activity and lyso-phosphatidylcholine (Lyso-PC) levels in ALS patients suggest that CE accumulation was driven by acyl group transfer from PC to cholesterol. Notably, Lyso-PC, a byproduct of CE synthesis, was toxic to human MNsin vitro. Elevations in CE, triacylglycerol, and Lyso-PC were also found in the spinal cord of SOD1G93Amice, a model of ALS. Similar to ALS patients, a compensatory downregulation of cholesterol synthesis occurred in the spinal cord of SOD1G93Amice; levels of sterol regulatory element binding protein 2, a transcriptional regulator of cholesterol synthesis, progressively declined. Remarkably, overexpressing sterol regulatory element binding protein 2 in the spinal cord of normal mice to model CE accumulation led to ALS-like lipid pathology, MN death, astrogliosis, paralysis, and reduced survival. Thus, spinal cord lipid dysregulation in ALS likely contributes to neurodegeneration and developing therapies to restore lipid homeostasis may lead to a treatment for ALS.SIGNIFICANCE STATEMENTNeurons that control muscular function progressively degenerate in patients with amyotrophic lateral sclerosis (ALS). Lipid dysregulation is a feature of ALS; however, it is unclear whether disrupted lipid homeostasis (i.e., lipid cacostasis) occurs proximal to degenerating neurons in the spinal cord, what causes it, and whether it contributes to neurodegeneration. Here we show that lipid cacostasis occurs in the spinal cord gray matter of ALS patients. Lipid accumulation was not associated with an aberrant increase in synthesis or reduced hydrolysis, as enzymatic and transcriptional regulators of lipid synthesis were downregulated during disease. Last, we demonstrated that genetic induction of lipid cacostasis in the CNS of normal mice was associated with ALS-like lipid pathology, astrogliosis, neurodegeneration, and clinical features of ALS.

Mutations in the glucocerebrosidase gene (GBA) confer a heightened risk of developing Parkinson's disease (PD) and other synucleinopathies, resulting in a lower age of onset and exacerbating disease progression. However, the precise mechanisms by which mutations in GBA increase PD risk and accelerate its progression remain unclear. Here, we investigated the merits of glucosylceramide synthase (GCS) inhibition as a potential treatment for synucleinopathies. Two murine models of synucleinopathy (a Gaucher-related synucleinopathy model, GbaD409V/D409V and a A53T-α-synuclein overexpressing model harboring wild-type alleles of GBA, A53T-SNCA mouse model) were exposed to a brain-penetrant GCS inhibitor, GZ667161. Treatment of GbaD409V/D409V mice with the GCS inhibitor reduced levels of glucosylceramide and glucosylsphingosine in the central nervous system (CNS), demonstrating target engagement. Remarkably, treatment with GZ667161 slowed the accumulation of hippocampal aggregates of α-synuclein, ubiquitin, and tau, and improved the associated memory deficits. Similarly, prolonged treatment of A53T-SNCA mice with GZ667161 reduced membrane-associated α-synuclein in the CNS and ameliorated cognitive deficits. The data support the contention that prolonged antagonism of GCS in the CNS can affect α-synuclein processing and improve behavioral outcomes. Hence, inhibition of GCS represents a disease-modifying therapeutic strategy for GBA-related synucleinopathies and conceivably for certain forms of sporadic disease.

Spinal muscular atrophy is a progressive motor neuron disease caused by a deficiency of survival motor neuron. In this study, we evaluated the efficacy of intravenous administration of a recombinant adeno-associated virus (AAV1) vector encoding human insulin-like growth factor-1 (IGF-1) in a severe mouse model of spinal muscular atrophy. Measurable quantities of human IGF-1 transcripts and protein were detected in the liver (up to 3 months postinjection) and in the serum indicating that IGF-1 was secreted from the liver into systemic circulation. Spinal muscular atrophy mice administered AAV1-IGF-1 on postnatal day 1 exhibited a lower extent of motor neuron degeneration, cardiac and muscle atrophy as well as a greater extent of innervation at the neuromuscular junctions compared to untreated controls at day 8 posttreatment. Importantly, treatment with AAV1-IGF-1 prolonged the animals' lifespan, increased their body weights and improved their motor coordination. Quantitative polymerase chain reaction and western blot analyses showed that AAV1-mediated expression of IGF-1 led to an increase in survival motor neuron transcript and protein levels in the spinal cord, brain, muscles, and heart. These data indicate that systemically delivered AAV1-IGF-1 can correct several of the biochemical and behavioral deficits in spinal muscular atrophy mice through increasing tissue levels of survival motor neuron.

Metabolic dysfunction is an important modulator of disease course in amyotrophic lateral sclerosis (ALS). We report here that a familial mouse model (transgenic mice over-expressing the G93A mutation of the Cu/Zn superoxide dismutase 1 gene) of ALS enters a progressive state of acidosis that is associated with several metabolic (hormonal) alternations that favor lipolysis. Extensive investigation of the major determinants of H + concentration (i.e., the strong ion difference and the strong ion gap) suggests that acidosis is also due in part to the presence of an unknown anion. Consistent with a compensatory response to avert pathological acidosis, ALS mice harbor increased accumulation of glycogen in CNS and visceral tissues. The altered glycogen is associated with fluctuations in lysosomal and neutral α-glucosidase activities. Disease-related changes in glycogen, glucose, and α-glucosidase activity are also found in spinal cord tissue samples of autopsied patients with ALS. Collectively, these data provide insights into the pathogenesis of ALS as well as potential targets for drug development.

Mutations in GBA1, the gene encoding glucocerebrosidase, are associated with an enhanced risk of developing synucleinopathies such as Parkinson's disease (PD) and dementia with Lewy bodies. A higher prevalence and increased severity of motor and non-motor symptoms is observed in PD patients harboring mutant GBA1 alleles, suggesting a link between the gene or gene product and disease development. Interestingly, PD patients without mutations in GBA1 also exhibit lower levels of glucocerebrosidase activity in the central nervous system (CNS), implicating this lysosomal enzyme in disease pathogenesis. Here, we investigated whether modulation of glucocerebrosidase activity in murine models of synucleinopathy (expressing wild type Gba1) affected α-synuclein accumulation and behavioral phenotypes. Partial inhibition of glucocerebrosidase activity in PrP-A53T-SNCA mice using the covalent inhibitor conduritol-B-epoxide induced a profound increase in soluble α-synuclein in the CNS and exacerbated cognitive and motor deficits. Conversely, augmenting glucocerebrosidase activity in the Thy1-SNCA mouse model of PD delayed the progression of synucleinopathy. Adeno-associated virus-mediated expression of glucocerebrosidase in the Thy1-SNCA mouse striatum led to decrease in the levels of the proteinase K-resistant fraction of α-synuclein, amelioration of behavioral aberrations and protection from loss of striatal dopaminergic markers. These data indicate that increasing glucocerebrosidase activity can influence α-synuclein homeostasis, thereby reducing the progression of synucleinopathies. This study provides robust in vivo evidence that augmentation of CNS glucocerebrosidase activity is a potential therapeutic strategy for PD, regardless of the mutation status of GBA1.

Niemann-Pick disease Type A (NPA) is a neuronopathic lysosomal storage disease (LSD) caused by the loss of acid sphingomyelinase (ASM). The goals of the current study are to ascertain the levels of human ASM that are efficacious in ASM knockout (ASMKO) mice, and determine whether these levels can be attained in non-human primates (NHPs) using a multiple parenchymal injection strategy. Intracranial injections of different doses of AAV1-hASM in ASMKO mice demonstrated that only a small amount of enzyme (10 mg hASM/g tissue was reached. In monkeys, injection of 12 tracts of AAV1-hASM resulted in efficacious levels of enzyme in broad regions of the brain that was aided, in part, by axonal transport of adeno-associated virus (AAV) and movement through the perivascular space. This study demonstrates that a combination cortical, subcortical, and cerebellar injection protocol could provide therapeutic levels of hASM to regions of the NHP brain that are highly affected in NPA patients. The information from this study might help design new AAV-mediated enzyme replacement protocols for NPA and other neuronopathic LSDs in future clinical trials.

Central nervous system (CNS)-directed gene therapy with recombinant adeno-associated virus (AAV) vectors has been used effectively to slow disease course in mouse models of several neurodegenerative diseases. However, these vectors were typically tested in mice without prior exposure to the virus, an immunological scenario unlikely to be duplicated in human patients. Here, we examined the impact of pre-existing immunity on AAV-mediated gene delivery to the CNS of normal and diseased mice. Antibody levels in brain tissue were determined to be 0.6% of the levels found in systemic circulation. As expected, transgene expression in brains of mice with relatively high serum antibody titers was reduced by 59–95%. However, transduction activity was unaffected in mice that harbored more clinically relevant antibody levels. Moreover, we also showed that markers of neuroinflammation (GFAP, Iba1, and CD3) and histopathology (hematoxylin and eosin (H&E)) were not enhanced in immune-primed mice (regardless of pre-existing antibody levels). Importantly, we also demonstrated in a mouse model of Niemann Pick Type A (NPA) disease that pre-existing immunity did not preclude either gene transfer to the CNS or alleviation of disease-associated neuropathology. These findings support the continued development of AAV-based therapies for the treatment of neurological disorders.

One treatment approach for lysosomal storage diseases (LSDs) is the systemic infusion of recombinant enzyme. Although this enzyme replacement is therapeutic for the viscera, many LSDs have central nervous system (CNS) components that are not adequately treated by systemic enzyme infusion. Direct intracerebroventricular (ICV) infusion of a high concentration of recombinant human acid sphingomyelinase (rhASM) into the CNS over a prolonged time frame (hours) has shown therapeutic efficacy in a mouse model of Niemann–Pick A (NP/A) disease. To evaluate whether such an approach would translate to a larger brain, rhASM was infused into the lateral ventricles of both rats and Rhesus macaques, and the resulting distribution of enzyme characterized qualitatively and quantitatively. In both species, ICV infusion of rhASM resulted in parenchymal distribution of enzyme at levels that were therapeutic in the NP/A mouse model. Enzyme distribution was global in nature and exhibited a relatively steep gradient from the cerebrospinal fluid compartment to the inner parenchyma. Additional optimization of an ICV delivery approach may provide a therapeutic option for LSDs with neurologic involvement.

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by motor neuron cell loss, muscular atrophy, and a shortened life span. Survival is highly variable, as some patients die within months, while others live for many years. Exposure to stress or the development of a nonoptimal stress response to disease might account for some of this variability. We show in the SOD1G93A mouse model of ALS that recurrent exposure to restraint stress led to an earlier onset of astrogliosis and microglial activation within the spinal cord, accelerated muscular weakness, and a significant decrease in median survival (105 vs. 122 d) when compared to nonstressed animals. Moreover, during normal disease course, ALS mice display a cacostatic stress response by developing an aberrant serum corticosterone circadian rhythm. Interestingly, we also found that higher corticosterone levels were significantly correlated with both an earlier onset of paralysis (males: r2=0.746; females: r2=0.707) and shorter survival times (males: r2=0.680; females: r2=0.552) in ALS mice. These results suggest that stress is capable of accelerating disease progression and that strategies that modulate glucocorticoid metabolism might be a viable treatment approach for ALS.—Fidler, J. A., Treleaven, C. M., Frakes, A., Tamsett, T. J., McCrate, M., Cheng, S. H., Shihabuddin, L. S., Kaspar, B. K., Dodge, J. C. Disease progression in a mouse model of amyotrophic lateral sclerosis: the influence of chronic stress and corticosterone.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the progressive loss of upper and lower motor neurons. However, recent reports suggest an active role of non-neuronal cells in the pathogenesis of the disease. Here, we examined quantitatively the temporal development of neuropathologic features in the brain and spinal cord of a mouse model of ALS (SOD1(G93A)). Four phases of the disease were studied in both male and female SOD1(G93A) mice: presymptomatic (PRE-SYM), symptomatic (SYM), endstage (ES) and moribund (MB). Compared to their control littermates, SOD1(G93A) mice showed an increase in astrogliosis in the motor cortex, spinal cord and motor trigeminal nucleus in the SYM phase that worsened progressively in ES and MB animals. Associated with this increase in astrogliosis was a concomitant increase in motor neuron cell death in the spinal cord and motor trigeminal nucleus in both ES and MB mice, as well as in the ventrolateral thalamus in MB animals. In contrast, microglial activation was significantly increased in all the same regions but only when the mice were in the MB phase. These results suggest that astrogliosis preceded or occurred concurrently with neuronal degeneration whereas prominent microgliosis was evident later (MB stage), after significant motor neuron degeneration had occurred. Hence, our findings support a role for astrocytes in modulating the progression of non-cell autonomous degeneration of motor neurons, with microglia playing a role in clearing degenerating neurons.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by motor neuron cell death in the cortex, brainstem, and spinal cord. Extensive efforts have been made to develop trophic factor-based therapies to enhance motor neuron survival; however, achievement of adequate therapeutic delivery to all regions of the corticospinal tract has remained a significant challenge. Here, we show that adeno-associated virus serotype 4 (AAV4)-mediated expression of insulin-like growth factor-1 (IGF-1) or vascular endothelial growth factor (VEGF)-165 in the cellular components of the ventricular system including the ependymal cell layer, choroid plexus [the primary cerebrospinal fluid (CSF)-producing cells of the central nervous system (CNS)] and spinal cord central canal leads to trophic factor delivery throughout the CNS, delayed motor decline and a significant extension of survival in SOD1(G93A) transgenic mice. Interestingly, when IGF-1- and VEGF-165-expressing AAV4 vectors were given in combination, no additional benefit in efficacy was observed suggesting that these trophic factors are acting on similar signaling pathways to modestly slow disease progression. Consistent with these findings, experiments conducted in a recently described in vitro cell culture model of ALS led to a similar result, with both IGF-1 and VEGF-165 providing significant motor neuron protection but in a nonadditive fashion. These findings support the continued investigation of trophic factor-based therapies that target the CNS as a potential treatment of ALS.

Niemann-Pick A (NPA) disease is a lysosomal storage disorder (LSD) caused by a deficiency in acid sphingomyelinase (ASM) activity. Previously, we showed that the storage pathology in the ASM knockout (ASMKO) mouse brain could be corrected by intracerebral injections of cell, gene and protein based therapies. However, except for instances where distal areas were targeted with viral vectors, correction of lysosomal storage pathology was typically limited to a region within a few millimeters from the injection site. As NPA is a global neurometabolic disease, the development of delivery strategies that maximize the distribution of the enzyme throughout the CNS is likely necessary to arrest or delay progression of the disease. To address this challenge, we evaluated the effectiveness of intracerebroventricular (ICV) delivery of recombinant human ASM into ASMKO mice. Our findings showed that ICV delivery of the enzyme led to widespread distribution of the hydrolase throughout the CNS. Moreover, a significant reduction in lysosomal accumulation of sphingomyelin was observed throughout the brain and also within the spinal cord and viscera. Importantly, we demonstrated that repeated ICV infusions of ASM were effective at improving the disease phenotype in the ASMKO mouse as indicated by a partial alleviation of the motor abnormalities. These findings support the continued exploration of ICV delivery of recombinant lysosomal enzymes as a therapeutic modality for LSDs such as NPA that manifests substrate accumulation within the CNS.

Pompe disease (glycogen storage disease II) is caused by mutations in the acid α-glucosidase gene. The most common form is rapidly progressive with glycogen storage, particularly in muscle, that leads to profound weakness, cardiac failure, and death by the age of two years. Although usually considered a muscle disease, glycogen storage also occurs in the CNS. We evaluated the progression of neuropathological and behavioral abnormalities in a Pompe disease mouse model (6neo/6neo) that displays many features of the human disease. Homozygous mutant mice store excess glycogen within large neurons of hindbrain, spinal cord, and sensory ganglia by the age of one month; accumulations then spread progressively within many CNS cell types. “Silver degeneration” and Fluoro-Jade C stains revealed severe degeneration in axon terminals of primary sensory neurons at three to nine months. These abnormalities were accompanied by progressive behavioral impairment on rotorod, wire hanging and foot fault tests. The extensive neuropathological alterations in this model suggest that therapy of skeletal and cardiac muscle disorders by systemic enzyme replacement therapy may not be sufficient to reverse functional deficits due to CNS glycogen storage, particularly early-onset, rapidly progressive disease. A better understanding of the basis for clinical manifestations is needed to correlate CNS pathology with Pompe disease manifestations.

Niemann–Pick A disease (NPD-A) is caused by a deficiency of acid sphingomyelinase (ASM) leading to the intracellular accumulation of sphingomyelin and cholesterol in lysosomes. We evaluated the effects of direct intraparenchymal brain injections of purified recombinant human ASM (hASM) at correcting the storage pathology in a mouse model of NPD-A (ASMKO). Different doses (0.1 ng to 10 μg of hASM) were injected into the right hemisphere of the hippocampus and thalamus of 12- to 14-week-old ASMKO mice. Immunohistochemical analysis after 1 week indicated that animals treated with greater than 1 μg hASM/site showed detectable levels of enzyme around the injected regions. However, localized clearance of sphingomyelin and cholesterol storage were observed in animals administered lower doses of enzyme, starting at 100 ng hASM/site. Areas of correction were also noted at distal sites such as in the contralateral hemispheres. Indications of storage re-accumulation were seen after 2 weeks post-injection. Injections of hASM did not cause any significant cell infiltration, astrogliosis, or microglial activation. These results indicate that intraparenchymal injection of hASM is associated with minimal toxicity and can lead to regional reductions in storage pathology in the ASMKO mouse.

Niemann-Pick disease (NPD) is caused by the loss of acid sphingomyelinase (ASM) activity, which results in widespread accumulation of undegraded lipids in cells of the viscera and CNS. In this study, we tested the effect of combination brain and systemic injections of recombinant adeno-associated viral vectors encoding human ASM (hASM) in a mouse model of NPD. Animals treated by combination therapy exhibited high levels of hASM in the viscera and brain, which resulted in near-complete correction of storage throughout the body. This global reversal of pathology translated to normal weight gain and superior recovery of motor and cognitive functions compared to animals treated by either brain or systemic injection alone. Furthermore, animals in the combination group did not generate antibodies to hASM, demonstrating the first application of systemic-mediated tolerization to improve the efficacy of brain injections. All of the animals treated by combination therapy survived in good health to an investigator-selected 54 weeks, whereas the median lifespans of the systemic-alone, brain-alone, or untreated ASM knockout groups were 47, 48, and 34 weeks, respectively. These data demonstrate that combination therapy is a promising therapeutic modality for treating NPD and suggest a potential strategy for treating disease indications that cause both visceral and CNS pathologies.

Recent genetic evidence suggests that aberrant glycosphingolipid metabolism plays an important role in several neuromuscular diseases including hereditary spastic paraplegia, hereditary sensory neuropathy type 1, and non-5q spinal muscular atrophy. Here, we investigated whether altered glycosphingolipid metabolism is a modulator of disease course in amyotrophic lateral sclerosis (ALS). Levels of ceramide, glucosylceramide, galactocerebroside, lactosylceramide, globotriaosylceramide, and the gangliosides GM3 and GM1 were significantly elevated in spinal cords of ALS patients. Moreover, enzyme activities (glucocerebrosidase-1, glucocerebrosidase-2, hexosaminidase, galactosylceramidase, α-galactosidase, and β-galactosidase) mediating glycosphingolipid hydrolysis were also elevated up to threefold. Increased ceramide, glucosylceramide, GM3, and hexosaminidase activity were also found in SOD1(G93A) mice, a familial model of ALS. Inhibition of glucosylceramide synthesis accelerated disease course in SOD1(G93A) mice, whereas infusion of exogenous GM3 significantly slowed the onset of paralysis and increased survival. Our results suggest that glycosphingolipids are likely important participants in pathogenesis of ALS and merit further analysis as potential drug targets.

Classical late infantile neuronal ceroid lipofuscinosis (cLINCL) is a lysosomal storage disorder caused by mutations inCLN2, which encodes lysosomal tripeptidyl peptidase I (TPP1). Lack of TPP1 results in accumulation of autofluorescent storage material and curvilinear bodies in cells throughout the CNS, leading to progressive neurodegeneration and death typically in childhood. In this study, we injected adeno-associated virus (AAV) vectors containing the human CLN2 cDNA into the brains ofCLN2−/−mice to determine therapeutic efficacy. AAV2CUhCLN2 or AAV5CUhCLN2 were stereotaxically injected into the motor cortex, thalamus, and cerebellum of both hemispheres at 6 weeks of age, and mice were then killed at 13 weeks after injection. Mice treated with AAV2CUhCLN2 and AAV5CUhCLN2 contained TPP1 activity at each injection tract that was equivalent to 0.5- and 2-fold that ofCLN2+/+control mice, respectively. Lysosome-associated membrane protein 1 immunostaining and confocal microscopy showed intracellular targeting of TPP1 to the lysosomal compartment. Compared with control animals, there was a marked reduction of autofluorescent storage in the AAV2CUhCLN2 and AAV5CUhCLN2 injected brain regions, as well as adjacent regions, including the striatum and hippocampus. Analysis by electron microscopy confirmed a significant decrease in pathological curvilinear bodies in cells. This study demonstrates that AAV-mediated TPP1 enzyme replacement corrects the hallmark cellular pathologies of cLINCL in the mouse model and raises the possibility of using AAV gene therapy to treat cLINCL patients.

Niemann-Pick type A disease is a lysosomal storage disorder caused by a deficiency in acid sphingomyelinase (ASM) activity. Previously we showed that storage pathology in the ASM knockout (ASMKO) mouse brain can be corrected by adeno-associated virus serotype 2 (AAV2)-mediated gene transfer. The present experiment compared the relative therapeutic efficacy of different recombinant AAV serotype vectors (1, 2, 5, 7, and 8) using histological, biochemical, and behavioral endpoints. In addition, we evaluated the use of the deep cerebellar nuclei (DCN) as a site for injection to facilitate global distribution of the viral vector and enzyme. Seven-week-old ASM knockout mice were injected within the DCN with different AAV serotype vectors encoding human ASM (hASM) and then killed at either 14 or 20 weeks of age. Results showed that AAV1 was superior to serotypes 2, 5, 7, and 8 in its relative ability to express hASM, alleviate storage accumulation, and correct behavioral deficits. Expression of hASM was found not only within the DCN, but also throughout the cerebellum, brainstem, midbrain, and spinal cord. This finding demonstrates that targeting the DCN is an effective approach for achieving widespread enzyme distribution throughout the CNS. Our results support the continued development of AAV based vectors for gene therapy of the CNS manifestations in Niemann-Pick type A disease.

Niemann-Pick A disease (NPA) is a fatal lysosomal storage disorder caused by a deficiency in acid sphingomyelinase (ASM) activity. The lack of functional ASM results in cellular accumulation of sphingomyelin and cholesterol within distended lysosomes throughout the brain. In this study, we investigated the potential of AAV-mediated expression of ASM to correct the brain pathology in an ASM knockout (ASMKO) mouse model of NPA. An AAV serotype 2 vector encoding human ASM (AAV2-hASM) was injected directly into the adult ASMKO hippocampus of one hemisphere. This resulted in expression of human ASM in all major cell layers of the ipsilateral hippocampus for at least 15 weeks postinjection. Transduced cells were also present in the entorhinal cortex, medial septum, and contralateral hippocampus in a pattern consistent with retrograde axonal transport of AAV2. There was a substantial reduction of distended lysosomes and an almost complete reversal of cholesterol accumulation in all areas of the brain that were targeted by AAV2-hASM. These findings show that the ASMKO brain is responsive to ASM replacement and that retrograde transport of AAV2 functions as a platform for widespread gene delivery and reversal of pathology in affected brain.

Mutations of GBA1 , the gene encoding glucocerebrosidase, represent a common genetic risk factor for developing the synucleinopathies Parkinson disease (PD) and dementia with Lewy bodies. PD patients with or without GBA1 mutations also exhibit lower enzymatic levels of glucocerebrosidase in the central nervous system (CNS), suggesting a possible link between the enzyme and the development of the disease. Previously, we have shown that early treatment with glucocerebrosidase can modulate α-synuclein aggregation in a presymptomatic mouse model of Gaucher-related synucleinopathy ( Gba1 D409V/D409V ) and ameliorate the associated cognitive deficit. To probe this link further, we have now evaluated the efficacy of augmenting glucocerebrosidase activity in the CNS of symptomatic Gba1 D409V/D409V mice and in a transgenic mouse model overexpressing A53T α-synuclein. Adeno-associated virus-mediated expression of glucocerebrosidase in the CNS of symptomatic Gba1 D409V/D409V mice completely corrected the aberrant accumulation of the toxic lipid glucosylsphingosine and reduced the levels of ubiquitin, tau, and proteinase K-resistant α-synuclein aggregates. Importantly, hippocampal expression of glucocerebrosidase in Gba1 D409V/D409V mice (starting at 4 or 12 mo of age) also reversed their cognitive impairment when examined using a novel object recognition test. Correspondingly, overexpression of glucocerebrosidase in the CNS of A53T α-synuclein mice reduced the levels of soluble α-synuclein, suggesting that increasing the glycosidase activity can modulate α-synuclein processing and may modulate the progression of α-synucleinopathies. Hence, increasing glucocerebrosidase activity in the CNS represents a potential therapeutic strategy for GBA1 -related and non- GBA1 –associated synucleinopathies, including PD.

The aim of the present study was to evaluate the suitability of an experimental latex as a controlled release coating dispersion by preparing, optimizing and characterizing pellets of ibuprofen. A laboratory size fluidized bed coating machine (Uniglatt M-2817) was used to coat ibuprofen loaded beads with the experimental latex to release 400 mg of ibuprofen in a 12 h period in pH 7.2 phosphate buffer. Independent variables such as solids content, volume of coating dispersion, and plasticizer concentration were optimized using a three-factor, three-level Box-Behnken design. The response studied was cumulative percentage dissolved in 12 h with constraints on 1, 6 and 12 h. Surface response plots were utilized to relate the dependent and the independent variables. The optimization procedure generated a maximum of 86% release in 12 h when the levels of solids content, volume of coating dispersion and plasticizer concentration were 11.06% w/w, 113.7 ml, and 26.59% w/w respectively. The optimized pellets prepared based on the predicted levels yielded response values which were close to the predicted values. The kinetics of release was shown to follow Baker-Lonsdale model. The formulations were characterized using DSC, SEM and X-ray diffraction studies. Comparative evaluation with other commercial preparations indicated that the experimental latex provides a more efficient release of the anionic drug, ibuprofen.

The efficacy of administering a recombinant adeno-associated virus (AAV) vector encoding human IGF-1 (AAV2/1-hIGF-1) into the deep cerebellar nucleus (DCN) of a type III SMA mouse model was evaluated. High levels of IGF-1 transcripts and protein were detected in the spinal cord at 2 months post-injection demonstrating that axonal connections between the cerebellum and spinal cord were able to act as conduits for the viral vector and protein to the spinal cord. Mice treated with AAV2/1-hIGF-1 and analyzed 8 months later showed changes in endogenous Bax and Bcl-xl levels in spinal cord motor neurons that were consistent with IGF-1-mediated anti-apoptotic effects on motor neurons. However, although AAV2/1-hIGF-1 treatment reduced the extent of motor neuron cell death, the majority of rescued motor neurons were non-functional, as they lacked axons that innervated the muscles. Furthermore, treated SMA mice exhibited abnormal muscle fibers, aberrant neuromuscular junction structure, and impaired performance on motor function tests. These data indicate that although CNS-directed expression of IGF-1 could reduce motor neuron cell death, this did not translate to improvements in motor function in an adult mouse model of type III SMA.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease of the motor system. Recent work in rodent models of ALS has shown that insulin-like growth factor-1 (IGF-1) slows disease progression when delivered at disease onset. However, IGF-1's mechanism of action along the neuromuscular axis remains unclear. In this study, symptomatic ALS mice received IGF-1 through stereotaxic injection of an IGF-1-expressing viral vector to the deep cerebellar nuclei (DCN), a region of the cerebellum with extensive brain stem and spinal cord connections. We found that delivery of IGF-1 to the central nervous system (CNS) reduced ALS neuropathology, improved muscle strength, and significantly extended life span in ALS mice. To explore the mechanism of action of IGF-1, we used a newly developed in vitro model of ALS. We demonstrate that IGF-1 is potently neuroprotective and attenuates glial cell-mediated release of tumor necrosis factor-alpha (TNF-alpha) and nitric oxide (NO). Our results show that delivering IGF-1 to the CNS is sufficient to delay disease progression in a mouse model of familial ALS and demonstrate for the first time that IGF-1 attenuates the pathological activity of non-neuronal cells that contribute to disease progression. Our findings highlight an innovative approach for delivering IGF-1 to the CNS.

Late infantile neuronal ceroid lipofuscinosis (LINCL) is an autosomal recessive neurodegenerative disease caused by mutations in CLN2, which encodes the lysosomal protease tripeptidyl peptidase 1 (TPP1). LINCL is characterized clinically by progressive motor and cognitive decline, and premature death. Enzyme-replacement therapy (ERT) is currently available for lysosomal storage diseases affecting peripheral tissues, but has not been used in patients with central nervous system (CNS) involvement. Enzyme delivery through the cerebrospinal fluid is a potential alternative route to the CNS, but has not been studied for LINCL. In this study, we identified relevant neuropathological and behavioral hallmarks of disease in a mouse model of LINCL and correlated those findings with tissues from LINCL patients. Subsequently, we tested if intraventricular delivery of TPP1 to the LINCL mouse was efficacious. We found that infusion of recombinant human TPP1 through an intraventricular cannula led to enzyme distribution in several regions of the brain of treated mice. In vitro activity assays confirm increased TPP1 activity throughout the rostral–caudal extent of the brain. Importantly, treated mice showed attenuated neuropathology, and decreased resting tremor relative to vehicle-treated mice. This data demonstrates that intraventricular enzyme delivery to the CNS is feasible and may be of therapeutic value.

Classical late infantile neuronal ceroid lipofuscinosis (cLINCL) is a monogenic disorder caused by the loss of tripeptidyl peptidase 1 (TPP1) activity as a result of mutations in CLN2. Absence of TPP1 results in lysosomal storage with an accompanying axonal degeneration throughout the central nervous system (CNS), which leads to progressive neurodegeneration and early death. In this study, we compared the efficacies of pre- and post-symptomatic injections of recombinant adeno-associated virus (AAV) for treating the cellular and functional abnormalities of CLN2 mutant mice. Intracranial injection of AAV1-hCLN2 resulted in widespread human TPP1 (hTPP1) activity in the brain that was 10–100-fold above wild-type levels. Injections before disease onset prevented storage and spared neurons from axonal degeneration, reflected by the preservation of motor function. Furthermore, the majority of CLN2 mutant mice treated pre-symptomatically lived for at least 330 days, compared with a median survival of 151 days in untreated CLN2 mutant controls. In contrast, although injection after disease onset ameliorated lysosomal storage, there was evidence of axonal degeneration, motor function showed limited recovery, and the animals had a median lifespan of 216 days. These data illustrate the importance of early intervention for enhanced therapeutic benefit, which may provide guidance in designing novel treatment strategies for cLINCL patients.

Amytrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that is characterized by a selective loss of motor neurons in the motor cortex, brain stem and spinal cord. The etiology of motor neuron degeneration remains largely unknown. Although chronic delivery of therapeutic agents to the central nervous system has proven to be difficult, recent studies have demonstrated that intramuscular delivery of adeno-associated viral vectors encoding insulin growth factor 1 (AAV-IGF-1) slowed disease progression and extended survival in SOD1G93A mice. The efficacy of viral mediated expression of IGF-1 was mediated in part by the ability of the viral vector to undergo retrograde transport from muscle to motor neurons. Previously we demonstrated that targeting the deep cerebellar nuclei (DCN) of the cerebellum with viral vectors capable of axonal transport resulted in detection of transgene protein in both the brain stem and spinal cord (Dodge et al. 2005, PNAS 102:17822-17827). In this experiment we evaluated the efficacy of bilateral delivery of AAV1|[ndash]|IGF-1 and AAV2-IGF-1 to the DCN in 90 day old SOD1G93A mice. Starting at 80 days of age (and every 10 days thereafter), SOD1G93A mice underwent behavioral testing (rotarod, hindlimb and forelimb grip strength) to assess motor function. At 90 days of age (i.e., time point at which SOD1 mice exhibit overt disease symptoms of ALS) mice received stereotaxic bilateral injections of AAV1-IGF-I (n=26), AAV2-IGF-I (n=27), AAV1-GFP (n=26) or AAV2-GFP (n=25) aimed at the deep cerebellar nuclei (DCN) of the cerebellum. We found that bilateral delivery of AAV- IGF-1 treatment (regardless of serotype) to the DCN significantly promoted motor neuron survival, improved motor performance in both rotarod and grip strength behavioral tests and significantly extended lifespan (i.e., 12 day extension for AAV1-IGF-1 and 14 day extension for AAV2-IGF-1). Treatment with AAV-GFP had no effect on any of the parameters mentioned above. Our results indicate that direct administration of AAV-IGF-1 into the DCN modifies disease progression in a mouse model of ALS and that targeting the DCN with AAV vectors is an effective approach for delivering therapeutic transgenes to both the brain and spinal cord for the treatment of ALS.

Niemann-Pick disease is caused by a genetic deficiency in acid sphingomyelinase (ASM) leading to the intracellular accumulation of sphingomyelin and cholesterol in lysosomes. In the present study, we evaluated the effects of direct intracerebral transplantation of neural progenitor cells (NPCs) on the brain storage pathology in the ASM knock-out (ASMKO) mouse model of Type A Niemann-Pick disease. NPCs derived from adult mouse brain were genetically modified to express human ASM (hASM) and were transplanted into multiple regions of the ASMKO mouse brain. Transplanted NPCs survived, migrated, and showed region-specific differentiation in the host brain up to 10 weeks after transplantation (the longest time point examined).In vitro, gene-modified NPCs expressed up to 10 times more and released five times more ASM activity into the culture media compared with nontransduced NPCs.In vivo, transplanted cells expressed hASM at levels that were barely detectable by immunostaining but were sufficient for uptake and cross-correction of host cells, leading to reversal of distended lysosomal pathology and regional clearance of sphingomyelin and cholesterol storage. Within the host brain, the area of correction closely overlapped with the distribution of the hASM-modified NPCs. No correction of pathology occurred in brain regions that received transplants of nontransduced NPCs. These results indicate that the presence of transduced NPCs releasing low levels of hASM within the ASMKO mouse brain is necessary and sufficient to reverse lysosomal storage pathology. Potentially, NPCs may serve as a useful gene transfer vehicle for the treatment of CNS pathology in other lysosomal storage diseases and neurodegenerative disorders.

Recent experiments completed in mice indicate that sex significantly influences adeno-associated virus (AAV) transduction efficiency in the liver suggesting that hormones may modulate the activity of AAV. The present study aimed to determine what influence sex and estrous cycle stage have on AAV transduction (as inferred from expression levels) in the rodent brain. Adult C57BL/6 mice and Sprague-Dawley rats were unilaterally injected within the thalamus, hippocampus and cortex with either AAV2/1-ASM or AAV2/2-ASM, and then sacrificed 4 weeks later. Vaginal smears were performed immediately following surgery to determine cycle stage at the time of vector delivery. A cohort of juvenile mice underwent a similar experimental procedure with AAV, but at an age (i.e., 3 weeks) when sex differences in circulating hormone levels are absent. Rodent brain homogenates were analyzed for ASM protein levels by ELISA. In both adult mice and rats, ASM protein levels (irrespective of AAV serotype vector used) were significantly higher in males than females. In adult mice, estrous cycle stage also significantly influenced AAV mouse brain transduction activity. ASM levels were highest in females in diestrus and lowest in females in proestrus. ASM protein levels in estrous female mice were intermediate between female mice classified in diestrus and proestrus |[ndash]| all groups were significantly different from each other. These results indicate that there is a negative relationship between AAV-mediated protein expression in the female mouse brain and circulating hormone levels. Consistent with hormonal influences on these results, non-cycling, juvenile mice did not exhibit sex differences in ASM protein expression levels within the CNS. Experiments are currently underway to determine which hormone(s) is/are responsible for the observed sex differences in AAV transduction in the rodent brain.

Niemann-Pick A (NPA) disease is a lysosomal storage disorder (LSD) caused by a deficiency in acid sphingomyelinase (ASM) activity. Previously, we reported that biochemical and functional abnormalities observed in ASM knockout (ASMKO) mice could be partially alleviated by intracerebroventricular (ICV) infusion of hASM. We now show that this route of delivery also results in widespread enzyme distribution throughout the rat brain and spinal cord. However, enzyme diffusion into CNS parenchyma did not occur in a linear dose-dependent fashion. Moreover, although the levels of hASM detected in the rat CNS were determined to be within the range shown to be therapeutic in ASMKO mice, the absolute amounts represented less than 1% of the total dose administered. Finally, our results also showed that similar levels of enzyme distribution are achieved across rodent species when the dose is normalized to CNS weight as opposed to whole body weight. Collectively, these data suggest that the efficacy observed following ICV delivery of hASM in ASMKO mice could be scaled to CNS of the rat.

The majority of lysosomal storage diseases contain both CNS and visceral pathology. Many experimental designs use either intracranial injection of viral vectors to treat the neurodegenerative phenotype of the disease, or systemic delivery to treat the viscera. In this study, we tested whether a combination of brain and systemic injections of adeno-associated virus (AAV) vectors could increase lifespan, provide whole body reversal of pathology, and improve motor and cognitive function in the acid sphingomyelinase knock out (ASMKO) mouse model of Niemann-Pick disease. ASMKO mice at 4 weeks of age were injected systemically with AAV8- hASM, and subsequently, the same animals were injected into the brain with AAV2-hASM. All the mice treated by combination injections survived to 54 weeks of age. This was a significant improvement over untreated ASMKO mice, animals that had been treated by systemic injection only or by brain injection only, which had median life spans of 34 weeks, 45 weeks, and 43 weeks, respectively. Thus the brain alone injections did not protect animals from dying. Animals treated by the combination therapy also displayed normal weight gain, and significant functional recovery on the rotarod (motor task) and the Barnes maze (cognitive task) throughout the time course of the study. These data support the contention that combination therapy can improve the quality of life before and within the time frame of extended survival.

Recombinant adeno-associated virus serotypes-1 and -2 encoding human acid sphingomyelinase were administered into multiple structures of the cynomolgus monkey brain using convection- enhanced delivery. One group of monkeys (n = 2) was injected with 30|[ndash]|100 ul of AAV2-hASM into the striatum, thalamus, motor cortex and hippocampus, and euthanized at 31 days post-injection. Transduction occurred in the four injected structures and in other regions that resulted in an expression pattern that spanned 50|[ndash]|60 mm, although the posterior aspects of the brain had only sporadic human ASM-positive cells. In situ hybridization experiments demonstrated that widespread transduction was aided, in part, by retrograde axonal transport of AAV2 and by movement of the viral vector through the perivascular space. A second group of monkeys (n = 2) was injected with 30-50 ul of AAV1-hASM into the same four structures, as well as into the occipital cortex and cerebellum to achieve more efficient transduction of caudal brain structures. At 35 days post-injection, widespread transduction by AAV1 was observed in both the injected structures and in other regions along the rostro-caudal axis of the brain, including robust transduction of posterior aspect of the brain. In situ hybridization experiments confirmed retrograde axonal transport of AAV1 to multiple regions of the brain, including the medulla oblongata that sends axonal projections to the cerebellum. Furthermore, the horizontal transduction pattern in the neuronal layers of the convoluted cortex strongly suggests that AAV1 (and AAV2) may become widely dispersed by moving along the outside of major white matter tracts. This study demonstrate that the topographical organization of the brain circuits, and the anatomical features of the Virchow-Robin space and white matter tracts, may be exploited to achieve widespread gene/protein delivery in the primate brain including remote regions of that are not accessible by surgery.

Niemann-Pick A disease (NPA) is a lysosomal storage disorder caused by a deficiency in acid sphingomyelinase (ASM) activity. Consequent accumulation of sphingomyelin and other lipids in the CNS results in the development of a rapidly progressive neurodegenerative disease with death occurring by 2 to 3 years of age. Previously we have shown that the storage pathology in the ASM knockout (ASMKO) mouse brain is amenable to AAV2/2-mediated gene therapy. Interestingly, correction of storage pathology occurred not only at the injection site, but also in regions that send and/or receive input from the injection site|[ndash]|suggesting that AAV vector and/or expressed ASM protein underwent transport. The present experiment evaluated the relative ability of recombinant AAV2/1, AAV2/2, AAV2/5, AAV2/7 and AAV2/8 serotype vectors encoding human ASM to facilitate gene transduction, express ASM protein, correct cholesterol storage pathology, undergo transport, rescue Purkinje cells, and initiate functional recovery in the ASMKO mouse. Male ASMKO mice (|[sim]|7 weeks old) were unilaterally injected with the different AAV serotype vectors within the deep cerebellar nuclei of the cerebellum (DCN). The DCN was targeted because it is highly connected with the CNS; and therefore, may provide a means to achieve widespread ASM expression throughout the brain. Mice were sacrificed at 14 weeks of age after undergoing rotarod testing. Mice injected with AAV2/1 and AAV2/8 demonstrated significant functional improvement on the rotarod, whereas mice injected with AAV2/2, AAV2/5 and AAV2/7 did not. Consistent with the behavioral results, cerebellar ASM protein levels (as detected by ELISA) were significantly higher in mice injected with AAV2/1 and AAV2/8, than mice injected with AAV2/2, AAV2/5, AAV2/7 and control mice. Preservation of Purkinje cells based on calbindin immunostaining was greatest in mice injected with AAV2/1 and AAV2/8. In all AAV-ASM treated mice, expression of ASM led to widespread clearance of filipin/cholesterol staining in the cerebellum, brainstem, and midbrain|[ndash]|indicating that AAV vector and/or expressed ASM underwent transport from the DCN. Overall, a positive relationship between ASM protein levels, filipin clearance, Purkinje cell survival, and rotarod performance was observed. These results support the further evaluation of AAV2/1 and AAV2/8-based vectors for gene therapy of the CNS manifestations in Niemann-Pick A disease.

Top of pageAbstract Type A Niemann-Pick disease (NPA) is a fatal neurometabolic childhood disorder caused by a genetic deficiency of acid sphingomyelinase (ASM). The lack of functional ASM results in sphingomyelin and cholesterol accumulation within the lysosomal compartment of cells throughout the brain, leading to neurodegeneration. In this study, we investigated the efficacy of using AAV gene therapy as a form of ASM enzyme replacement to correct lysosomal pathology and to prevent Purkinje cell death in a mouse ASM knockout (ASMKO) model of NPA. An AAV serotype-2 vector encoding human ASM under the control of CMV promoter (AAV2-CMV-ASM) was injected into the adult hippocampus of one hemisphere. This resulted in human ASM mRNA and protein expression in all major cell layers of the ipsilateral hippocampus for up to 15 weeks post-injection. Transduced cells were also present in the entorhinal cortex, medial septum, supramammillary nucleus, and contralateral hippocampus in a pattern consistent with retrograde transport of AAV2. There was a substantial reduction of distended lysosomal pathology and an almost complete reversal of cholesterol accumulation in all brain regions expressing human ASM. Following injection of AAV2-CMV-ASM into other brain regions (e.g. striatal and cerebellar circuits), we observed a similar pattern of local and distant (retrograde) transduction and reversal of pathology. Within the cerebellum of ASMKO mice, there is an almost complete loss of Purkinje cells between 7 and 20 weeks of age. AAV2-CMV-ASM was injected into the ASMKO cerebellum between 5 and 7 weeks, and treated mice were sacrificed 15 weeks later (20–22 weeks old). These injections resulted in neuroprotection as evidenced by the preservation of large numbers of human ASM mRNA- and protein-positive Purkinje cells within treated lobules. We also found that intraventricular injection of juvenile (3 week old) ASMKO mice resulted in Purkinje cell transduction, human ASM expression and survival for up to 18 weeks post-injection. These results demonstrate that viral vector delivery via the cerebrospinal fluid is an effective way to target Purkinje cells for genetic manipulation. We are currently investigating different promoters and AAV serotypes for vector optimization. To this end, we have generated an AAV serotype-1 vector encoding human ASM under the control of chicken beta-actin promoter (AAV1-CBA-ASM). Administration into the cerebrum resulted in long-term human ASM expression and widespread clearance of cholesterol deposits for up to 26 weeks. Preliminary results have also shown that injection of AAV1-CBA-ASM into the cerebellum of young ASMKO mice preserved rotorod performance, a test sensitive to proprioceptive deficits caused, in part, by Purkinje cell degeneration. In conclusion, our data show that AAV-mediated human ASM enzyme replacement therapy leads to long-lasting, widespread reversal of lysosomal storage pathology, neuroprotection and functional sparing in the ASMKO mouse model of NPA.