Scientists uncover compound that frees trapped cholesterol

January 27th, 2009 - 4:17 pm ICT by ANI  

Washington, January 27 (ANI): Scientists at UT Southwestern Medical Center have identified a compound that can free cholesterol that has inappropriately accumulated to excessive levels inside cells.
The researchers say that their discovery in mice shed light on how cholesterol is transported through the cells of the body, and suggest a possible therapeutic target for Niemann-Pick type C disease (NP-C), an inherited neurodegenerative disorder characterized by abnormally high cholesterol levels in every organ.
What weve shown is that very quickly after administration of this compound, the huge pool of cholesterol that has just been accumulating in the cells is suddenly released and metabolized normally, said Dr. John Dietschy, professor of internal medicine at UT Southwestern.
With just one dose, you excrete a large portion of this pool of cholesterol, he added.
Cholesterol in the body comes from dietary sources, and is also made by the body itself. It is essential for many biological processes, including the construction and maintenance of cell membranes.
Normally, it is transported through cells, and excreted by the body.
People with Niemann-Pick type C have a genetic mutation that causes excessive amounts of cholesterol to accumulate in compartments within cells called lysosomes.
The vast majority of children diagnosed with NP-C die before they are 20 years old and many before age 10.
This cholesterol accumulation leads to liver disease, neurodegeneration and dementia. There is no specific level at which cholesterol levels become abnormal.
Late onset of neurological symptoms such as clumsiness, mild retardation and delayed development of fine motor skills can lead to longer life spans, but few people diagnosed with NP-C reach age 40.
For the current study, the researchers injected a single dose of a cholesterol-binding agent known as CYCLO into seven-day-old mice with the Niemann-Pick mutation. Shortly afterwards, such mice began to process cholesterol just as their healthy counterparts did.
After 49 days, the mice treated with a single injection continued to show substantially lower tissue cholesterol levels than the untreated mice, as well as improved liver function and decreased neurodegeneration.
Dr. Dietschy cautioned that the findings in no way represent a Niemann-Pick disease cure.
The key idea is that we appear to have overcome the transport defect in the lysosome that is brought about by the genetic defect or mutation. We do not yet understand what is happening at the molecular level, but it is clear that this compound somehow overcomes the genetic defect that causes individuals to accumulate cholesterol, Dr. Dietschy said.
The researcher revealed that the next step would be to find out the concentration of CYCLO needed to trigger the cholesterols release.
The team also hope to determine in animals the additional lifespan CYCLO administration provides, as well as how long the drugs affects lasts.
By treating at seven days, we eliminated approximately one-third of the accumulated cholesterol almost immediately. Now we want to see what happens if we give it every week. Can we maintain low cholesterol levels? Thats what were looking at now, Dr. Dietschy said.
The study has been published in the online edition of the Proceedings of the National Academy of Sciences. (ANI)

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