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Multiple Sclerosis, The Blood Brain Barrier, and New Treatment:

Simplified Version

by R. Stout

Abstract: Survey of Journal articles shows preponderance of evidence that Multiple Sclerosis attacks occur during breakdowns of the blood-brain barrier. Other articles show that flavonoids including those found in blueberries and grape seeds amongst others can inhibit blood-brain barrier breakdown in rats under conditions which normally lead to such breakdown. The same flavonoids can also be effective in reducing inflammation, which might thus have value in treating the symptoms of an exacerbation. Suggested experiments are proposed to evaluate whether flavonoids may offer effective treatment for multiple sclerosis.

This article is a simplification of a highly technical article written for those with a background in biology or medicine. For the complete version: Enter

Posted on the internet at http://spider.lloyd.com/~tstout/articles/ms-simplified.html on June 17, 1996. This is a rewrite of earlier versions posted June 2, 1996 and May 23, 1996 .

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For a long time multiple sclerosis has been a puzzling disease. Recent experimental studies have clarified many of the problems associated with the disease.

Historically, it has been known that MS is caused by certain white blood cells attacking the myelin surrounding the nerve cells of a person's own central nervous system. This was looked at as a defect in the immune system and much work was concentrated in trying to explain MS simply as an autoimmune disease. However, the disease was much too erratic to fit the autoimmune models with any satisfaction.

Overlooked during these studies was a more fundamental question, "How did the white blood cells get to the myelin in order to attack it to begin with?" Under normal conditions the blood-brain barrier (BBB) provides an effective separation between the blood cells and the myelin, such that it would be irrelevant whether or not some of the white cells were programmed incorrectly. Hence, the question presents itself as to whether or not there is evidence of BBB malfunction during MS attacks.

The BBB is a feature of the blood capillaries found in the central nervous system. Capillaries are made a very thin "tube" barely wide enough for one blood cell at a time to pass through. They transport nutrients and remove waste products from the individual cells of the body near them. The walls of the capillaries are made of cells only one layer in thickness. In most parts of the body these wall cells are quite loosely joined together, providing a relative free flow of materials between the capillary and the surrounding tissue. Within the central nervous system, however, the situation is different. The capillaries are cemented together very tightly with and only small particles can pass through the openings. This protects the brain and nerves of the spinal chord from attack by viruses and bacteria and other toxins. Under normal conditions the white blood cells would be prevented from passing through the blood-brain barrier. Thus, they should not have access to the myelin surrounding the nerve cells in order to attack it.

A recent computerized journal search at the University of California at Health Sciences Library with their biosis search engine revealed 214 journal articles that responded to keyword searches for both Multiple Sclerosis and Blood-Brain Barrier.

These articles show that within the research community it is becoming understood that the breakdowns in the BBB are a key step in the formation of a new MS lesion.

For example, an article published in March of 1996 demonstrated that when MRI scans were made on a weekly basis, that of 38 observed new lesions, every single one of them was preceeded by a breakdown in the blood-brain barrier. (Ref 1)

Although many other articles could be quoted tying together MS attacks and BBB breakdown, the above article expresses the matter quite clearly and for our purposes we will assume that further research will serve only to confirm and refine these findings and conclusions.

The true value of a good theory for the cause of a disease such as multiple sclerosis is the possibility of an effective treatment proceeding from the theory. In the light of the above discussion, a simple potential treatment presents itself: strengthen the BBB to the extent that no further breakdowns occur.

There are three related chemicals which have been found effective in strengthening the blood-brain barrier in animals. These are the anthocyanosides, proanthocyanidins, and procyanidolic oligomers (PCOs). All three of these are variants of a common class of chemicals called "flavonoids."

Anthocyanosides are the chemicals which give blueberries, cherries, and blackberries their color. Proanthocyanidins and their oligomers (PCOs) are found in purple grape skins and grape seeds and the bark and needles of certain pine trees. PCOs derived from pine bark are typically marketed under the trade name pycnogenols.

At the University of California at Health Sciences Library, there were two articles discussing the effect of anthocyanosides on the blood-brain barrier:

In one set of experiments the blood brain barrier was "opened" in test rats by placing various four different kinds of chemicals in the blood stream. Then anthocyanosides were injected into the blood stream of some but not all of the rats. The rats receiving anthocyanosides would recover their normal BBB strength in 24 hours, whereas those without the anthocyanosides would take 72 hours. Amongst the chemicals injected was collagenase, whose action is to weaken the glue cementing together the cells of the capillary walls. It is particularly noteworthy that the effects of this chemical were also overcome by the anthocyanosides. (Ref 2)

In an another set of experiments, rats were induced with BBB breakdown using another process. The experimenters' conclusions were that the anthocyanoside treatment was able to return the strength of the BBB back to normal in all of their experiments. (Ref 3)

Discussion

In both of these experiments anthocyanosides were able to strengthen the BBB in rats. The question becomes whether or not such strengthening would be effective for human patients suffering MS lesions. The target goal for the MS patient would be to keep the BBB strong enough such that no future lesions would occur. If this can be realized, the goal of much MS research may finally be reached. If no new lesions occur, the progressive of the disease will stop. Furthermore, the body does tend to repair the damage from exacerbations. This is what is observed during the recovery phase of RR MS. So, the expectation is that if the BBB could be strengthened such that no new attacks would occur, not only would the progress of the disease be stopped, but that a person might expect a certain amount of recovery as well.

It should be noted that these concepts are "leading edge"; it was only three months ago that the above journal article by Lei et al was printed (ref 1), in which evidence was given that in all 38 new lesions the researchers observed they also found evidence of BBB deficiency. The reason for this deficiency is unknown. Just because anthocyanoside treatment is effective in rats for the various mechanisms used to weaken the integrity of the BBB, this does not mean that it would necessarily be effective for MS. However, there were five different mechanisms used to degrade the BBB in the two articles we quoted and anthocyanosides were effective in strengthening the BBB in all five. So, because there were a number of different mechanisms used to degrade the BBB and since the anthocyanoside treatment was so general in effectiveness it may be anticipated that there would be a carry over from the rat to the human.

Another study also using rats was done on the permeability of blood vessels in general. In this case it was noted that if the rats were pretreated with PCOs (either grape-seed extract or pycnogenols) that a subsequent injection of collagenase did not lead to an increase in the flow rate in and out of the capillary walls. This is a similar experiment to ref 2 above, except in ref 2 the collagenase was given first and anthocyanosides speeded up recovery and in this experiment PCOs were given first and the PCOs kept the problem from occuring to begin with. ref 4 abstract This is important, because this is the very effect we want to achieve in our proposed treatment. I.e., by keeping the blood-brain barrier supplied with appropriate flavonoids (either anthocyanosides and/or PCOs), it is hoped that when something comes along that would normally have caused a breach in the BBB and a subsequent lesion, that instead the flavonoids will prevent the damage from occurring.

The glue which holds the cells of the capillary walls together, indeed, which actually holds all cells together, is called the "extracellular matrix." Certain cells in the immune system produce enzymes which can dissolve the extracellular matrix. For most parts of the body this is useful in allowing white blood cells greater access to an area of infection in order to fight the infection. However, when these cells release their chemicals in the capillaries within the CNS, there is a resulting breakdown of the BBB, leading to an MS lesion, at least in certain individuals. One of the chemicals which can be released by the white blood cells goes by the letters MMP. Although MMPs purpose is to weaken the intercellular cement, they are not active in the form in which they are released. They are activated by exposure to other enzymes. ref 5

There is another process at work which also has the potential to attack BBB integrity. When white blood cells destroy invading organisms, superoxides and free radicals are released. These superoxides and free radicals are extremely active and can destroy many of the tissues they contact. This results in a powerful anti-bacterial action. ref 6 So, the generation of superoxides and free radicals are useful against infections. However, when the process takes place at the blood-brain barrier, such as takes place at the beginning of an MS lesion, it can be just one more attack on the integrity of the barrier.

I would now like to discuss three proposed mechanisms by which flavonoids might be effective in MS treatment.

1). Flavonoids have a tremendous affinity for joining themselves to enzymes. Thus, if they were to join themselves to either the MMPs or their activators, they might be able to block this process. This would then be a specific mechanism by which the BBB would be preserved and an impending MS lesion thwarted.

One article tells how recent studies indicate that certain flavonoids have rather extraordinary capacities to inhibit the activity of many enzyme systems. Included in a listing of the enzyme systems inhibited by flavenoids are those that attack the extracellular matrix. ref 7 The mechanism we envision here is that when MMPs are released as discussed earlier, that the flavonoids would "disable" them before they joined with their activator enzyme. Thus, they would be rendered ineffective and a new lesion potentially avoided.

2) Flavonoids tend to penetrate and become part of the cellular matrix, or at least adhere to it. This is particularly true of the PCOs. While in the matrix, they have receptor sites exposed which tend to grab onto the enzymes which would otherwise attack the matrix. Thus, they become "sacrificial lambs" so to speak in maintaining the integrity of the matrix. In an experiment it was "conclusively evidenced that PCOs injected intradermally into young rabbits would bind to certain extracellular molecules . As a result, the molecules were found more resistant to attacking enzymes injected to the same site. These studies empahsized the potential effect of these PCOs in preventing extracellular degradation by certain enzymes which occur in inflammatory processes. In the same article a "test tube" experiment is discussed wherein the PCOs were shown to bind to representative molecules of the extracellular matrix and the PCOs completely inhibited them from being dissolved. ref 8 Although the specific molecule tested here was elastin and not collagen or any of the other components of the BBB matrix, it is reasonable to anticipate that the effects would have been similar if collagen had been tested instead. Indeed, that is what was done in an experiment studied in the next paragraph.

3) Flavonoids are potent anti-oxidants. Free flavonoids (i.e., those not bound in the matrix as discussed in the above paragraph) will rapidly destroy free radicals before the radicals do their damage. Although this is only a secondary issue, it could still be significant. In one experiment collagen taken from calf skin was exposed to super oxidants. It was found that the oxidants readily split the collagen into peptides of a relatively small size. ref 6 Thus, once inflammation starts in the blood brain barrier, any oxygen free radicals produced may be assumed to compound the attack on the BBB matrix, reinforcing the breakdown process. However, the authors showed that if the collagen were first soaked in anthocyanosides, allowing them to bind with the collagen, and next the collagen were rinsed so that there were no free anthocyanosides available, that the oxygen free radicals still had decreased ability to dissolve the collagen. Again, this is what we would like to accomplish in our efforts to prevent or reduce the number of new MS lesions by flavenoid treatment.

An extremely interesting experiment was performed with mice. Although MS does not naturally occur except with human beings, there is a disease called Experimental Autoimmune Encephalomyelitus (EAE) which behaves like MS. This diseased is induced experimentally in an animal such as a rat, mouse, or rabbit by artificially sensitizing the animal to proteins such as are found in its central nervous system. Once sensitized, the disease will progress in a fashion very similar to the naturally occurring human disease MS. In the experiment of interest, EAE was induced in mice. The progress of the disease was stopped by treating the mice with a particular drug. The function of the drug was to stop the action of MMPs, discussed earlier. When the drug was given to mice with EAE, the progress of the disease was "reversed". Again, this is exactly what we are trying to do. Although the drug used was protein-based and not a favonoid, flavonoids are known to have the same specific behavior as this drug and so we should anticipate the same results. This action was apparently caused by restoration of the damaged blood-brain barrier in the inflammatory phase of the disease... ref 9

Reducing Inflammation: A Potential Side Benefit

In addition to strengthening the integrity of cell walls in general, including those of the blood-brain barrier, flavonoids have yet another potential value for the MS patient. Specifically, certain flavonoids have the potential ability to reduce inflammation. Since much of the damage caused to the nerve cells during an MS exacerbation is due to the inflammation, this would give hope that the treatment we will recommend to prevent or reduce the number of exacerbations might have as a possible side benefit that of reducing the severity of an exacerbation as well.

"The developing plaque of MS contains large numbers of macrophages (scavenger cells), which appear to destroy myelin by digesting its proteins and lipids. Inhibitors of the enzymes responsible for this digestion might reduce the myelin destruction or even interfere with movement of the macrophages into and through the tissues." "Improvements in MS are often dramatic. Much of the improvement is thought to be due to a subsidence of swelling and inflammation." "The principle drugs used to treat acute exacerbations are those having major antiinflamatory properties." "All of the above-mentioned drugs (i.e. certain drugs used to reduce inflammation) have possible serious side effects and should only be used under the supervision of a physician." ref 10

So, inflammation is a serious feature of an exacerbation and the treatment of an acute attack typically centers on reducing inflammation with various drugs. Unfortunately, all of the drugs traditionally used have serious side effects.

"Anthocyanosides of natural origin have double-pharmacological action: (1) antidegenerative action ... (2) antiinflammatory action, which can be a direct reduction of capillary permeability or reduction of generation of inflammatory mediators. The dual antidegenerative and antiinflammatory action promises wide use of anthocyanosides and related drugs..." ref 11 abstract Thus, even though our primary goal was to strengthen the blood-brain barrier, we have the added bonus of inadvertently, simultaneously reducing inflammation as well. Furthermore, we anticipate our proposed treatment to be WITHOUT side effects.

"Outstanding inflammatory effects are displayed by ... and delphindin (delphindin is an anthocyanidin.) ref 12 abstract Thus, anthocyanidins have "outstanding" antiinflammatory effects.

Proposed Clinical Tests