A novel mouse model of Niemann-Pick type C disease carrying a D1005G-Npc1 mutation comparable to commonly observed human mutations.

We have identified a point mutation in Npc1 that creates a novel mouse model (Npc1(nmf164)) of Niemann-Pick type C1 (NPC) disease: a single nucleotide change (A to G at cDNA bp 3163) that results in an aspartate to glycine change at position 1005 (D1005G). This change is in the cysteine-rich luminal loop of the NPC1 protein and is highly similar to commonly occurring human mutations. Genetic and molecular biological analyses, including sequencing the Npc1(spm) allele and identifying a truncating mutation, confirm that the mutation in Npc1(nmf164) mice is distinct from those in other existing mouse models of NPC disease (Npc1(nih), Npc1(spm)). Analyses of lifespan, body and spleen weight, gait and other motor activities, as well as acoustic startle responses all reveal a more slowly developing phenotype in Npc1(nmf164) mutant mice than in mice with the null mutations (Npc1(nih), Npc1(spm)). Although Npc1 mRNA levels appear relatively normal, Npc1(nmf164) brain and liver display dramatic reductions in Npc1 protein, as well as abnormal cholesterol metabolism and altered glycolipid expression. Furthermore, histological analyses of liver, spleen, hippocampus, cortex and cerebellum reveal abnormal cholesterol accumulation, glial activation and Purkinje cell loss at a slower rate than in the Npc1(nih) mouse model. Magnetic resonance imaging studies also reveal significantly less demyelination/dysmyelination than in the null alleles. Thus, although prior mouse models may correspond to the severe infantile onset forms of NPC disease, Npc1(nmf164) mice offer many advantages as a model for the late-onset, more slowly progressing forms of NPC disease that comprise the large majority of human cases.

In vivo assessment of neurodegeneration in Niemann-Pick type C mice by quantitative T2 mapping and diffusion tensor imaging.

PURPOSE: To quantitatively and noninvasively assess neurological disease progression in a mouse model of Niemann-Pick type C (NPC) disease by measuring white matter status with magnetic resonance imaging (MRI) techniques of T2 mapping and diffusion tensor imaging (DTI). MATERIALS AND METHODS: Quantitative T2 and DTI experiments were performed in vivo in NPC disease model and control mice at three timepoints to quantify differences and changes in white matter with measurements of T2 relaxation and DTI parameters. Histological staining for myelin content was also performed at two timepoints to compare with the MRI findings. RESULTS: The results of the T2 and DTI measurements show significant differences in white matter areas of the brain in the NPC disease model compared to control mice at several timepoints, and were seen to change over time in both groups. CONCLUSION: The findings of this study suggest that quantitative MRI measurements may be suitable in vivo biomarkers of disease status for future studies of NPC disease models. The changes in white matter measurements between timepoints in both control and NPC disease groups suggest that white matter structures continue to change and develop over time in the NPC model and can be tracked with MRI techniques.

Pulmonary function and pathology in hydroxypropyl-beta-cyclodextin-treated and untreated Npc1⁻/⁻ mice.

Lung dysfunction is an important part of the pathology of the neurodegenerative disorder, Niemann-Pick C1 (NPC1). We have studied the pulmonary disease in the Npc1(NIH/NIH) mouse model. On histology, we find large numbers of alveolar foamy macrophages but no alveolar proteinosis. Lung weight as percent of body weight was markedly increased; using the flexiVent small animal ventilator (SCIREQ, Inc.), we find inspiratory capacity, elastance and hysterisivity to be increased while resistance was not changed. Cholesterol measurements show a doubling of lung cholesterol levels. Collagen is also increased. Treatment of Npc1(-/-) mice with hydroxypropyl-ß-cyclodextrin (HPBCD), despite efficacious effects in brain and liver, results in little difference from age-matched controls (using a CNS-expressed transgene to extend the life expectancy of the Npc1(-/-) mice) for these variables.

Co-treatment with probucol does not improve lung pathology in hydroxypropyl-ß-cyclodextrin-treated Npc1-/- mice.

We previously reported the altered pulmonary function and pathology found in the mouse model of infantile Niemann-Pick C1 disease, the Npc1-/- mouse. Despite its salutary properties on brain and liver parameters, we did not find efficacious effects of hydroxypropyl-ß-cyclodextrin (HPBCD) on pulmonary pathology. Since we had previously shown the beneficial effects of probucol on the somatic phenotype in the Npc1-/- mice, we have now studied the effects of combined therapy with HPBCD and probucol on the lung with mostly negative results. Body weight and lung weight for body weight were increased in parallel while inspiratory capacity for body weight was markedly decreased. Other physical, biochemical, and pulmonary function parameters were not much changed. There were trends towards improved lung elastance (p = 0.09) and compliance (p = 0.07).

Relative efficacy of nicotinamide treatment of a mouse model of infantile Niemann-Pick C1 disease.

Nicotinamide delivered in drinking water at about 2 g/kg/day significantly prolonged survival and showed a suggestive improvement on memory in the Npc1 nih / Npc1 nih mouse model of infantile NPC1 disease. It is likely that this role is due to its function as a histone deacetylase (HDAC) inhibitor although another HDAC inhibitor, valproic acid, was without effect. Nicotinamide could also work by preventing/reversing oxidative stress.

Extensive macrophage accumulation in young and old Niemann-Pick C1 model mice involves the alternative, M2, activation pathway and inhibition of macrophage apoptosis.

We have studied the pathophysiology of lung disease which occurs in two mouse models of Niemann-Pick C1 disease. We utilized Npc1(-/-) mice transgenic for normal gene expression in glia or neurons and glia at ages several fold the usual and a mouse model of the juvenile form of NPC1, a point mutation, at one age to confirm some findings. Lung weights, as per cent of body weight, increase much more than liver and spleen weights. Although pulmonary function parameters only vary for hysteresis between young and older Npc1(-/-) mice, they are markedly different than those found in normal control mice. Cholesterol accumulation continued in the older mice but sphingosine-1-phosphate was not increased. Bronchoalveolar lavage (BAL) showed a massive increase (26×) in the number of macrophages. Histologic examination from the older, transgenic Npc1(-/-) mice showed small foci of alveolar proteinosis and evidence of hemorrhage, as well as dense macrophage accumulation. A large subset of macrophages was immunopositive for Fizz1 or arginase-1, markers of the alternative activation pathway, while no Fizz1 or arginase-1 positive macrophages were found in wild-type mice. The percentage of marker positive macrophages was relatively stable at 5-10% at various ages and within the 2 transgenic models. Phosphohistone H3 and Ki67 showed low levels of proliferation of these macrophages. Apoptosis was prominent within lung capillary endothelial cells, but limited within macrophages. Thus, activation of the alternative pathway is involved in Niemann-Pick C1 associated pulmonary macrophage accumulation, with low proliferation of these cells balanced by low levels of apoptosis.

Genetic variation in the mouse model of Niemann Pick C1 affects female, as well as male, adiposity, and hepatic bile transporters but has indeterminate effects on caveolae.

We have previously shown that male Npc1 heterozygous mice (Npc1(+/-)), as compared to homozygous wild-type mice (Npc1(+/+)), both maintained on the "lean" BALB/cJ genetic background, become obese on a high fat but not on a low fat diet. We have now extended this result for female heterozygous mice. When fed high-fat diet, the Npc1(+/-) white adipose weight is also increased in females, therefore following the same trend as males. Bile transporters which had previously been found to be altered in Npc1(-/-) mice on a high fat diet, showed related, but small, changes in mRNA levels but large changes in protein expression. We have addressed the possible role of caveolae in these differences. It has long been known that caveolin 1 is increased in the liver (sex not specified) of Npc1(+/-) (compared to Npc1(+/+) and Npc1(-/-)) mice and in heterozygous cultured skin fibroblasts of NPC1 carriers. We now find that caveolin 1 is increased in male, but not female liver and female, but not male adipose tissue. The caveolin 1 increase was not accompanied by changes in another caveolar protein, polymerase1 and transcript release factor (Ptrf). The numbers of caveolae in female adipose cells could not be correlated with levels of caveolae. Thus, we conclude that Npc1 affects female as well as male obesity and bile transporters but that effects on caveolin 1 are not discernible.

Lack of efficacy of curcumin on neurodegeneration in the mouse model of Niemann-Pick C1.

In order to determine the efficacy of curcumin in ameliorating symptoms of neurodegeneration in the mouse model of Niemann-Pick C1, a variety of formulations and dosages of curcumin, one comparable to one previously reported as efficacious, were provided orally to Npc1(-/-)mice. Plasma levels of curcumin, survival, tests of motor performance, and memory (in some cases) were performed. We found variable, but mild, increases in survival (1.5% to 18%). The greatest increased survival occurred with the highest dose (which was unformulated) while the control for the lipidated formulation (containing phosphatidylcholine and stearic acid) had an equivalent impact and other formulations, while not significantly increased, are also not statistically different in effect from the highest dose. We conclude that curcumin is not a highly efficacious treatment for neurodegeneration in Npc1(-/-) mice. Phosphatidylcholine and stearic acid should be studied further.

Interactions of Npc1 and amyloid accumulation/deposition in the APP/PS1 mouse model of Alzheimer's.

Although Niemann-Pick C1 disease has frequently been called "juvenile Alzheimer's", the effects of introducing Npc1 mutations into a mouse model of Alzheimer's have not previously been performed. We have crossed Npc1 (+/-) mice with APP/PS1 "Alzheimer's" mice and studied Aß42 accumulation and amyloid plaque formation. Mice heterozygous for Npc1 and positive for the APP and PS1 transgenes accumulated Aß42 more rapidly than the APP/PS1 controls and this correlated, as expected, with the area of amyloid plaques. We conclude that the alterations of intracellular cholesterol present in Npc1 (+/-) mice can influence the progress of Alzheimer's disease in the APP/PS1 mouse model.