HUNTINGTONS - HOPE

A small molecule that normally helps a cell survive dehydration can also prevent the formation of protein aggregates that lead to Huntington's disease.

When a cell is exposed to salty conditions, or high osmolarity, water exits the cell, thereby increasing the concentration of proteins that are already in an extremely crowded environment. This stressful situation can lead to protein misfolding. To cope, the cell turns on a cell membrane pump that transports small molecules called osmolytes into the cell for damage control.

Given that osmolytes such as proline, trehalose, or ectoine help cellular proteins deal with stressful situations, biochemists at the University of Massachusetts, Amherst, wondered if osmolytes could work in pathological situations-for instance, by helping to prevent aggregation in protein-folding diseases like Huntington's. Proline proved their hunch (Proc. Natl. Acad. Sci. USA 2006, 103, 13357).

To test their theory, Lila Gierasch and Zoya Ignatova put together a protein chimera that favors partially unfolded states because it has a sequence of 53 glutamine residues attached at the end. Such strings of glutamine residues lead to protein aggregation and are the pathological agent of Huntington's disease. Using proline, the researchers blocked the unfolding-prone protein from forming aggregates and reversed the formation of small, early-stage aggregates in vitro and in vivo.

Proline works its magic by destabilizing an aggregation-prone intermediate, by breaking up small aggregates, and by stabilizing the native state of the protein, Gierasch said. The limitation is large, existing aggregates: Proline can prevent further accumulation but it cannot break up large aggregates, Gierasch pointed out. As such, using proline would be more prevention than cure.

Gierasch presented the work during a session of talks that celebrated her receipt of the Francis P. Garvan-John M. Olin Medal, which was cosponsored by the Divisions of Biological Chemistry and Biochemical Technology.

"Lila has shown very elegantly that one way a cell controls its folding environment is with osmolytes like proline. It's very nice work, very insightful," said Jeffrey F. Kelly, a protein-folding chemist at Scripps Research Institute, who also spoke at the session. "Proline prevents the aggregation of natively unfolded proteins, whose aggregation appears to cause Huntington's disease. Strategies that enhance osmolyte production could therefore serve to ameliorate aggregation diseases."

"Protein aggregation and misfolding reactions are also the bane of protein production and impede pharmaceutical drug development," wrote Mark T. Fisher of the University of Kansas in a Proceedings of the National Academy of Sciences commentary. He suggests that mixing proline along with other antiaggregation osmolytes such as trehalose could be used to "enhance everyone's protein-folding toolbox."

What is Huntington's Disease?
Huntington's disease (HD) results from genetically programmed degeneration of brain cells, called neurons, in certain areas of the brain. This degeneration causes uncontrolled movements, loss of intellectual faculties, and emotional disturbance. HD is a familial disease, passed from parent to child through a mutation in the normal gene. Each child of an HD parent has a 50-50 chance of inheriting the HD gene. If a child does not inherit the HD gene, he or she will not develop the disease and cannot pass it to subsequent generations. A person who inherits the HD gene will sooner or later develop the disease. Whether one child inherits the gene has no bearing on whether others will or will not inherit the gene. Some early symptoms of HD are mood swings, depression, irritability or trouble driving, learning new things, remembering a fact, or making a decision. As the disease progresses, concentration on intellectual tasks becomes increasingly difficult and the patient may have difficulty feeding himself or herself and swallowing. The rate of disease progression and the age of onset vary from person to person. A genetic test, coupled with a complete medical history and neurological and laboratory tests, helps physicians diagnose HD. Presymptomic testing is available for individuals who are at risk for carrying the HD gene. In 1 to 3 percent of individuals with HD, no family history of HD can be found.

At this time, there is no way to stop or reverse the course of HD. Now that the HD gene has been located, investigators are continuing to study the HD gene with an eye toward understanding how it cause disease in the human body.

Of all the diagnoses to receive from a physician, Huntington's disease must rate up there as one of the worst. For sufferers of the rare inherited disorder, which strikes in mid-adulthood and manifests itself as an excruciatingly predictable process of neurological decline, death arrives just when the doctors say it will. There is no cure.

Researchers at Israel's Weizmann Institute of Science in Rehovot have recently shown, however, that it is possible to explain the mechanisms by which this genetic time bomb maintains its remarkable precision. And if it's possible, they say, to explain such punctuality in molecular terms, then it's likely too that one day soon the operation of Huntington's may also be clarified - and, with a little luck, vanquished altogether.

It's all to do with gene segments called "trinucleotides" - little three-letter lengths of DNA which appear repeatedly in the gene which codes for Huntington's. If a certain trinucleotide appears less that 40 times in that particular chronomosomal chunk, then symptoms will not ensue. But if the sequence continues for more than 40 repeats to over 70, then the characteristic Huntington's abnormalities arise - a progressive decline in muscle control and some cognitive abilities - and proceed to rob the sufferer of independence, hope, and a future.

For many years, scientists have been aware that it is possible to map the age that Huntington's will appear and how quickly the disease will progress in a patient according to the number of times the sequence repeats in their DNA.

Traditionally, it was thought that this predictability was due to the build-up of a protein fragment containing the amino acid (glutamine) in the repeating triplet that eventually reached toxic levels. If the trinucleotide coded for glutamine, then it seemed to follow that the greater number of trinucleotide repeats, the more drastic the effect of the accumulated glutamine.

This theory does not, however, explain all of the clinical data. Why, for example, do patients with two copies of the Huntington's gene not exhibit symptoms earlier than those with a single copy? In addition, glutamine is not produced in every trinucleotide disease, but the correlation between sequence repeats and onset age follows the same order in each of them.

The Weizmann scientists looked at the evidence and realized that the actual mechanism at work could be completely different. In a paper published in the journal PLoS Computational Biology, biological chemistry and computer science research student Shai Kaplan suggests that the process behind Huntington's might have more to do with somatic mutations - changes in the number of DNA repeats that build up in our cells as they naturally renew themselves throughout our lives.

Using existing literature on some 20 similar trinucleotide repeat diseases, Kaplan, together with Professor Ehud Shapiro and Dr Shalev Itzkovitz, created a computer program able to simulate the process of cell division with reference to the number of DNA repeats, age of disease onset and rate of progress. Noticing a correlation between repeat sequence length and intensification of symptoms, the scientists postulated that Huntington's and similar diseases may be caused by the accumulation of DNA repeats - not of proteins such as glutamine.

The new model appears to fit all of the facts, but Kaplan, Shapiro and Itzkovitz now plan to test their theory further. The scientists will test the Huntington's theory in the laboratory, hoping to pursue their research towards some treatment method which slows down the rate of cell division - and transforms a terrifying diagnosis into something far more benign.

A protein is made up of a string of amino acids. As the amino acids are strung together, the protein begins to fold up on itself until it gets to its final three-dimensional (3D) shape. Normal, stable proteins have no problem maintaining their shapes and functions in the cell. However, the Huntington's proteins formed from the HD allele are not very stable on their own, so they form into clumps known as protein aggregation.

Scientists think that if these proteins can be stabilized before they are fully folded, the protein aggregations will not form. One research group set out to test just that idea. They found that disaccharides are good at stabilizing molecules with extra CAG repeats, and are therefore capable of preventing protein aggregation. Trehalose was the most effective stabilizer of all the disaccharides tested. The researchers think that trehalose works by binding directly to the glutamine repeat section (the extra part of the protein that usually makes it unstable), while leaving the normal proteins unaffected.

This initial success led the researchers to test trehalose in mice that have the mouse version of HD. (Trehalose was easily administered to the mice by putting the sugar in their drinking water.) The differences between the mice treated with trehalose and the untreated mice are thus far encouraging. According to these experiments, treated mice not only live longer than untreated mice, but also fewer of their nerve cells die. In addition, the treated mice walk more easily than untreated mice and they experience later onset of the physical symptoms associated with HD.

The prospect of using trehalose as a treatment for HD is very exciting because it is known to be generally safe and can be taken orally. However, there are many steps between an exciting prospect and an actual, safe treatment. Even if trehalose can be easily obtained in food or as a supplement, one should first consult a physician before taking trehalose to in hopes of treating HD. While the initial results are promising, we must remember that this was only one study conducted by one group, using mice as subjects, not humans. Trehalose has not even undergone the first stage of clinical trials. Moreover, the positive effects seen in mice do not guarantee that it will work or even be completely safe in humans with HD. Since trehalose is composed of glucose, some scientists think that it might be metabolised (broken down) before it can even get to the cells in the human brain. Others think that giving a treatment made of glucose could contribute to the already elevated risk of people with HD developing diabetes.
While the current study of trehalose in HD mice is an encouraging one, only future research will demonstrate its safety and effectiveness in treating HD in humans.

Part of Henry Lorin's qualifications to write this book came from his almost daily contact with the Alzheimer's victim in this book from the beginning of the illness in 1981 to death of the victim in 1999, at the age of 80.

Dr. Lorin graduated from the Medical University of South Carolina in 1981 with the Doctor of Dental Medicine Degree (DMD). Before dental school it is relevant that Lorin graduated from College as a chemistry major giving him a solid understanding of the scientific method when it comes to medical research.

Also relevant to a full understanding of this book is the fact that the Alzheimer's victim in this book was his beloved father-in-law, who also had been placed on statin drugs before his first signs of Alzheimers disease because of coronary artery blockage. His initial cholesterol levels in the mid three hundreds were brought down to just under two hundred by the use of statins and diet.

Alzheimers disease began in his father-in-law in1990, nine years before death. Prior to writing this book Dr. Lorin reviewed thousands of references taking a remarkable 77 pages in his book just to list them. That in itself is an incredible task of the type usually required only for major review articles.

Scientific investigations using electronic and other technologies enable scientists to see what the defective gene does to various structures in the brain and how it affects the body's chemistry and metabolism.

Laboratory animals are being bred in the hope of duplicating the clinical features of HD so that researchers can learn more about the symptoms and progression of HD. Investigators are implanting fetal tissue in rodents and nonhuman primates with the hope of understanding, restoring, or replacing functions typically lost by neuronal degeneration in individuals with HD.

Related areas of investigation include excitotoxicity (overstimulation of cells by natural chemicals found in the brain), defective energy metabolism (a defect in the mitochondria), oxidative stress (normal metabolic activity in the brain that produces toxic compounds called free radicals), tropic factors (natural chemical substances found in the human body that may protect against cell death).

May 5, 2008 (Houston) Huntington's is one of the most devastating health challenges known to humans. Huntington's is hereditary and children normally have the gene but do not develop the tremors until later in life. There is no known cure for this deadly neurodegenerative disease.
J. C. Spencer, CEO of The Endowment for Medical Research announced that the non-profit organization is seeking major funding for Huntington's clinical trials. "Meanwhile, we have designed a low budget self funding, self or family evaluation system, to gather needed data showing benefits from the sugar trehalose."

Laboratory animal research using trehalose has already shown that this sugar may be beneficial in some neurodegenerative diseases. Other research indicates that it may strengthen cell membrane under certain conditions.

The Endowment for Medical Research hopes to gather data from a few thousand participants . . .

The Endowment for Medical Research hopes to gather data from a few thousand participants over an extended period of time to provide important information toward future pilot surveys and clinical studies and published papers.

Trehalose is found in nature and has been tested to produce lower insulin and blood glucose responses than regular sugar. Trehalose is two glucose molecules uniquely bonded together resulting in a sugar about 45% as sweet as table sugar with a very clean taste and can replace the sugar in your sugar bowl.

Trehalose is a disaccharide (two sugar) molecule composed of two smaller glucose molecules linked together. It is naturally produced by the body and can also be found in common foods. The U.S. Food and Drug Administration lists trehalose as a compound under the category of "generally regarded as safe." Since trehalose is a sugar, it is used as a sweetener in products such as chewing gum. It also has a very important property that helps it to stabilize proteins and can thus be used as a biological preservative. It is this very feature that may useful for treating Huntington's disease.
To read more about Trehalose click here

Mechanism of Action: Resveratrol stimulates the activity (directly or indirectly) of an enzyme called SIRT1, which is known to up regulate key metabolic and anti-inflammatory pathways that protect cells. This is probably the same protective mechanism that is activated by calorie restriction. Both resveratrol and calorie restriction can increase mitochondrial number and improve mitochondrial energy function. Both can decrease inflammation and chronic oxidative DNA injury. All of these effects are important for Huntington's.

Evidence for Potential Benefit in HD: First, scientists showed that calorie restriction delays onset of symptoms and extends the life of a genetic HD mouse [Duan 2003]. Scientists have also studied resveratrol and found it to be neuroprotective in several models of HD. This includes a nematode (worm) model and neurons (in cell culture) derived from a genetic HD mouse [Parker 2005]. More scientists have shown its benefit in the toxin mouse model of HD [Kumar 2006]. Lending more support for resveratrol neuroprotection, a recent study shows that it gives benefit (when injected directly into ventricles in brain) in mouse models of Alzheimer's disease and Amyotrophic Lateral Sclerosis [Kim 2007].

Resveratrol is on the SET-HD list, but was not chosen as an agent for initial review; nor is it listed as an agent being studied at CHDI.

Should We Take this Supplement? The correct answer is not known. Resveratrol may be beneficial if enough of it can get to the right place. But there are at least two substantial problems.

First, there is disagreement about dose needed for people. Sirtris Pharmaceuticals Inc. is using high doses in phase I human trials (2500 mg and 5000 mg per day) in their clinical trial of this drug for diabetes. Dr. David Sinclair, whose laboratory performed resveratrol mouse studies, has stated that lower doses may be beneficial. In an interview in the New York Times, he stated that he is taking a resveratrol supplement in smaller doses (5 mg/kg/day) than that used in the clinical trial. This smaller dose translates to 300-400 mg a day for people of average weight.

While most scientists not directly involved in the study suggest it is premature to take more than that available in one or two glasses of wine (about 1 or 2 mg/5 oz), there is no evidence that this dosage is beneficial. The dosage used in the clinical trial or by Dr. Sinclair is not attainable from wine or any other natural source.

Second, resveratrol is degraded quickly when exposed to oxygen. For instance, it is no longer active in wine if the bottle has been opened 24 hrs. The same applies to supplement preparations exposed to air during manufacture or storage. Most likely, the majority of marketed preparations don't contain the advertised active form.

Supplement Information: Longevinex (Greenpower in Europe) claims its manufacturing technique prevents degradation and has published results from (outside) lab testing that shows continued activity in capsules stored for 10 months. Further, this company claims to be sponsoring a human clinical trial using this product, and if so, must meet a higher level of manufacturing standard than other companies. But it's pricey: a little more than a dollar per each 100 mg pill.

There is little information available on the bioactivity of other over the counter brands. Consumer Lab states they are testing resveratrol supplements with results expected later in 2007. If you choose to use this supplement, Longevinex is probably your best alternative. A review in World Science gives background on the politics of resveratrol development, lists food sources, and gives additional supplement information.

Comments: At HDDW, we don't give definitive recommendations on any supplement or drug because there is no definitive clinical trial evidence. But we do give proactive information on those that have greatest possibilty of benefit based on the limited evidence that is available. The evidence base for each supplement or drug varies greatly. Some have only test tube evidence. Up a notch are those that have model organism (worm, fly, mouse) evidence. Much further along are those that are in human clinical trial for other neurodegenerative diseases, or better, are planned for HD. This means that they have passed the first hurdles in people; human safety and some documentation that the agent gets into brain.

We clearly favor those that are highest on this list. But remember, this does not mean that others with lesser evidence won't be helpful. Should you use resveratrol? The answer is still out.