Chronic Cyclodextrin Treatment of Murine Niemann-Pick C Disease Ameliorates Neuronal Cholesterol and Glycosphingolipid Storage and Disease Progression

Abstract

BackgroundNiemann-Pick type C (NPC) disease is a fatal neurodegenerative disorder caused most commonly by a defect in the NPC1 protein and characterized by widespread intracellular accumulation of unesterified cholesterol and glycosphingolipids (GSLs). While current treatment therapies are limited, a few drugs tested in Npc1−/− mice have shown partial benefit. During a combination treatment trial using two such compounds, N-butyldeoxynojirimycin (NB-DNJ) and allopregnanolone, we noted increased lifespan for Npc1−/− mice receiving only 2-hydroxypropyl-β-cyclodextrin (CD), the vehicle for allopregnanolone. This finding suggested that administration of CD alone, but with greater frequency, might provide additional benefit.Methodology/Principal FindingsAdministration of CD to Npc1−/− mice beginning at either P7 or P21 and continuing every other day delayed clinical onset, reduced intraneuronal cholesterol and GSL storage as well as free sphingosine accumulation, reduced markers of neurodegeneration, and led to longer survival than any previous treatment regime. We reasoned that other lysosomal diseases characterized by cholesterol and GSL accumulation, including NPC disease due to NPC2 deficiency, GM1 gangliosidosis and mucopolysaccharidosis (MPS) type IIIA, might likewise benefit from CD treatment. Treated Npc2−/− mice showed benefits similar to NPC1 disease, however, mice with GM1 gangliosidosis or MPS IIIA failed to show reduction in storage.Conclusions/SignificanceTreatment with CD delayed clinical disease onset, reduced intraneuronal storage and secondary markers of neurodegeneration, and significantly increased lifespan of both Npc1−/− and Npc2−/− mice. In contrast, CD failed to ameliorate cholesterol or glycosphingolipid storage in GM1 gangliosidosis and MPS IIIA disease. Understanding the mechanism(s) by which CD leads to reduced neuronal storage may provide important new opportunities for treatment of NPC and related neurodegenerative diseases characterized by cholesterol dyshomeostasis.

Endocytosis of beta-cyclodextrins is responsible for cholesterol reduction in Niemann-Pick type C mutant cells

“…6). This is consistent with the observation in npc1 −/− mice that CD treatments reduce levels of storage of other lipids in addition to cholesterol (12).…”

“…This is consistent with its better ability to extract cholesterol from biologic membranes (13)(14)(15). This observation may be important because relatively high amounts of HPβCD need to be injected to obtain a partial therapeutic effect (8)(9)(10)(11)(12). Additionally, the observation that CD works from inside LE/LY suggests that modifications that target CDs for endocytic uptake and retention might significantly enhance its potency.…”

“…Clinical manifestations of NPC disease include neuronal degeneration, hepatosplenomegaly, and effects in other organs (1). No effective treatment is currently available for NPC disease (7), but recent studies involving administration of hydroxypropyl-β-cyclodextrin (HPβCD) in npc1 −/− mice showed improvements in viability, hepatopathology, and neuropathology, including clearance of cholesterol and glycosphingolipids (8)(9)(10)(11)(12). These animal studies were not designed to address the molecular and cellular mechanisms by which cyclodextrins (CDs) could reduce the cholesterol accumulation in LSOs.…”

Altered vitamin E status in Niemann-Pick type C disease

“…Serum and appropriate tissues from Npc1 Ϫ / Ϫ and Npc2 Ϫ / Ϫ mice and their wild-type littermates were freshly excised and fl ash-frozen as described previously ( 45 ). Lipids were extracted, silylated, and analyzed by GC-MS on a Hewlett-Packard 6890 gas chromatograph coupled to a HewlettPackard 5872 mass selective detector operated in selected ion mode as previously described ( 46 ).…”

“…5G ). This could be explained by the fact that lipid accumulation is balanced by lipid loss that accompanies neurodegeneration in this tissue ( 6,45,73,79 ). Figure 6 shows the concentrations of tocopherol and cholesterol in plasma samples from Npc1 Ϫ / Ϫ , Npc2 Ϫ / Ϫ , and wild-type mice.…”