Funding for 2001

Noradrenaline Deficient Mice as a Model for FMS

Principal Investigator: Luc Jasmin, M.D., Ph.D.
University of California at San Francisco
Award: $56,925 - July 2001

Wouldn't it be great to have an animal model for FMS in which therapies could be quickly and easily tested? Then medications such as morphine, which ought to obliterate the pain of FMS instead of just reducing it by 25-50%, could be tested to determine if the addition of some other chemical that works on the pain system might boost its action. These two goals are the primary aims of Jasmin's project.

With the aid of an NIH grant received two years ago, Jasmin has already looked at the effects of reduced levels of noradrenaline (NA) in rats. Not all the NA was depleted from the rats and the process was only temporary. However, when the NA was low, the rats were very pain sensitive and produced excessive amounts of substance P, a situation that is analogous to that of people with FMS. When the NA levels returned to normal (about two weeks later), the rats no longer showed any signs of being in pain.

The results from this ongoing study prompted Jasmin to take a genetic approach to modeling FMS. For the AFSA-funded project, he will study the pain behavior of mice that are missing the gene that codes for the enzyme that is needed for making NA. Despite the lack of NA in their nervous system, these mice develop normally ... just like FMS patients who show no obvious signs of disease. Yet, these mice show symptoms similar to FMS, such as increased pain responses to mild pain stimuli (hyperalgesia), difficulty in concentration on tasks, tiredness, and dysfunction of the autonomic nervous system (e.g., the "auto-pilot" system that controls heart rate, breathing, responses to stress, digestion, etc.).

In the coming year, Jasmin will be examining these mice to see if substance P is involved in producing their hyperalgesia. Because nerve growth factor is also significantly elevated in people with FMS, Jasmin will be looking at this substance as well. Key to his studies in these mice is that NA can be restored, allowing him to ensure that it is the absence of NA and not some unrecognized developmental effect of the gene deletion that is responsible for his findings. It is hoped that both the symptoms and the biochemical abnormalities (high levels of substance P and nerve growth factor) will make this mouse a reliable model for further evaluating new therapies for FMS as well as its underlying physiology.

Jasmin is taking his project one step further. He will also be looking at a therapy that should be highly effective for controlling FMS pain: morphine. Jasmin will test the pain relieving effects of this opioid by itself and in conjunction with adding NA . He hopes to determine if the low NA levels (which are known to be present in FMS patients) could be the reason why opioids do not work as optimally as they should in FMS. If so, then the addition of medications that increase NA could also boost the pain relieving action of opioids in people with FMS.

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Autoimmune Mechanisms of Disordered Pain Perception

Principal Investigator: Thomas Fasy, M.D., Ph.D.
Mount Sinai School of Medicine, New York
Award: $58,400 - March 2001

It is now well established that our bodies make natural anti-pain substances known as endorphins or endogenous opioids. These endogenous opioids are peptides, (i.e., very small proteins). From a chemical or structural point of view, they are quite distinct from morphine or demeral. Yet, from a functional or pharmacological point of view, they exert amazingly similar effects on the central nervous system. These effects include a marked dampening of pain perception (i.e., reduction in pain), an enhanced sense of well-being or even euphoria, a suppression of anxiety, and an improved ability to tolerate stress. Clearly, the endogenous opioid peptides constitute a class of neurotransmitters that, if somehow disturbed, could have important ramifications in producing the symptoms of FMS.

The first endogenous opioids, the enkephalins, were discovered in 1975. Beta-endorphin is one of the more commonly referred to enkephalins, but simply measuring beta-endorphin alone to determine if the body's internal opioid system is working okay would be a terrible oversight by today's standards. Currently more than 20 endogenous opioid peptides have been identified. In fact, the endomorphins (which are morphine-like substances) and nocistatin (another novel opioid peptide) were discovered as recently as 1997 and 1998, respectively. Consequently, it is possible that additional endogenous opioids produced by the human body still remain undiscovered. Moreover, all of the mechanisms by which these recently discovered endogenous opioids work have not yet been extensively studied and their involvement in painful diseases such as FMS remains unclear.

Despite all the new advances in medical research, the underlying cause(s) of FMS remain a mystery. Given the new insights that have developed in the area of endogenous opioids, it begs the question of whether any of these molecules could be disrupted, destroyed, or somehow inadequately produced in people with FMS—and it was Dr. Fasy who first came to AFSA with this question two years ago.

In Fasy's first award from AFSA (June 1999), he looked for the presence of antibodies to more than a dozen neuropeptide molecules. These antibodies could deplete or destroy important pain relieving substances produced by the body and, if present, Fasy postulated that they could be involved in generating the symptoms of FMS. First he screened ten strains of mice that might be producing such antibodies. Fasy found one particular strain that produced an abundance of antibodies to a few important neuropeptides that could attack pain-relieving substances, particularly the body's enkephalins and historphin. Historphin works not only to reduce pain but also is reported in the medical literature to influence various hormonal (endocrine) actions in the body, including bone mineralization. So, a dysregulation of historphin by antibodies might plausibly contribute to the hormonal abnormalities reported in FMS.

As it turns out, this mouse strain displays many of the symptoms of FMS, but more testing on pain sensitivity needs to be done. They are timid and lack aggression, suggesting the possibility that this strain of mice are excessively fatigued. Fasy has further analyzed how the antibodies produced in high quantity might be working in the mice ... and potentially in human FMS patients as well. These data were presented at the American College of Rheumatology (ACR) meeting last November. Fasy was interviewed at that time and the answers to certain aspects of his research are below.

Several features of FMS suggest the possibility that these patients have a neuroendocrine imbalance which might very well include either a suboptimal response to or a deficiency of endogenous opioids. Such a deficiency could result not only from insufficient synthesis of one or more endogenous opioids, but also from an acceleration of their breakdown or hastening of their removal from the fluids which bathe the nervous system (these latter two modes could be due to the production of autoantibodies).

Fasy's second award builds on the exciting findings of his first AFSA-funded study. He will now test the hypothesis that, in many patients with FMS, the opioid peptide signaling network is disrupted by autoantibodies which bind to enkephalins, nocistatin, or historphin. This should prevent their normal functions and create an autoantibody-induced depletion of these essential endogenous opioids needed for relieving many FMS-like symptoms. A second goal of this project is to develop mouse models which will make it possible to study the extent to which enkephalin-, nocistain-, and historphin-binding autoantibodies perturb normal mouse behavior, especially responses to mildly noxious stimuli.

First blood sera from 30 patients with primary FMS (but no other disease), 30 healthy controls, and 20 patients with secondary FMS (FMS plus another rheumatic disease such as lupus or RA), will be screened. This amounts to a total of 80 samples from project collaborator, I. Jon Russell, M.D., Ph.D., of UT at San Antonio. Then the next step in the project will be to identify the most significant autoantibody findings in the sera and analyze for these same autoantibodies in the cerebral spinal fluid taken from the same subjects from which the sera was drawn (naturally all sorts of symptom data have been recorded by Russell for all study participants as well). The most remarkable and consistent findings in FMS to date have been uncovered in the spinal fluid, such as several-fold increases in substance P and nerve growth factor concentrations. Thus, this latter phase of the project may be where the most "golden" findings are discovered.

Based on just preliminary findings from this study, Fasy was successful in getting three scientific posters accepted for presentation at the September MYOPAIN 2001 meeting in Portland, OR. With a wealth of experience in molecular biology and genetics, autoimmune diseases, and pathology, it is now hoped that these two projects will launch Dr. Fasy into a career in FMS as well! What follows are the answers to just three of many questions that you might have regarding Fasy's exciting studies:

Q - When physicians order an autoantibody panel for a patient, which would include the ANA test, the findings typically come back negative. Does this mean that all autoimmune causes for their symptoms can be ruled out?

A - No, this approach doesn't cover the whole waterfront because the standard ANA test fails to detect some antinuclear antibodies. The binding sites on certain nuclear antigens may be buried and not accessible, so they just don't generate a colorful staining pattern that is needed for identifying antibodies with the standard test kits that are commercially available at laboratories. (In other words, Fasy's results can only be found in a high-tech research setting at this point in time, but it is possible to develop a standard test kit down the road, if warranted.)

Q - What about therapy options for patients who test positive for antibodies that may be destroying their enkephalins?

A - There are numerous potentially useful drugs that have been developed in the test tube that are awaiting clinical trials. So pharmacological interventions may be possible.

Q - The enkephalins mostly act on the delta opioid receptor, yet it is the mu receptor that morphine and other available opioids work on. What do you think about the work presented by AFSA-funded researcher Haiko Sprott, M.D., who found an 81-fold increase in the mRNA for the delta opioid receptor in the skin of FMS patients?

A - I think that disturbances of delta opioid receptors, which might also be called "enkephalin-receptors," may play a very important role in FMS. Maybe a small or large fraction of FMS patients have some difficulty in producing the enkephalin molecule that binds to delta opioid receptors to activate them. Perhaps there are autoantibodies or other processes accelerating the removal of enkephalins needed for turning on the delta receptor that delivers pain relief in the tissues.

(Fasy points out that promising delta opioid agonist drugs—which activate the delta opioid receptor—have already been developed by Astra Zenera, Smith-Kline-Beecham and other major pharmaceutical companies, but are still in the testing phase.)

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Opioid Receptors in the Skin and Muscle Tissue of FMS Patients - Part 2

Principal Investigator: Haiko Sprott, M.D.
Zurich, Switzerland
Award: $25,000 - April 2001

The purpose of Part 1 of Dr. Sprott's study was to look at the expression of opioid receptors on the cell surfaces of both skin and muscle tissue, with a focus on patients with FMS. There are three major types of opioid receptors: mu, kappa, and delta. Sprott measured the distribution of these various receptors in the skin and muscle tissue, and compared it to the normal brain tissue of one deceased age-matched woman. At the October 2000 American College of Rheumatology (ACR) meeting, he provided data that showed for the first time that a high population of opioid receptors, particularly kappa and delta, reside outside the central nervous system (i.e., the brain tissue). On the other hand, the mu receptor was not found in the skin and muscle tissues of healthy controls—only in the brain tissue.

Most prescription opioids work on the mu receptor, meaning that they must act within the central nervous system (CNS) and this can usually lead to unwanted side effects at doses needed to effectively alleviate the pain. Now that Sprott has established that the peripheral tissues are densely populated with delta and kappa opioid receptors (in particular the skin of FMS patients), this opens up other opportunities to treat pain without having to deal with the CNS side effects.

Preliminary data comparing the expression of delta and kappa opioid receptors in the skin and muscle tissue of FMS patients to that of healthy age-matched controls was also presented by Sprott and his colleague Souzan Salemi, Ph.D., at the ACR meeting. Based on half of the people to be tested, an 81-fold increase in delta and a 14-fold increase in kappa opioid receptors were found in the skin of FMS patients. Ironically, no differences could be found for these same receptors in the muscle tissues.

The findings in the muscle tissues may seem odd at first, because most patients will say that their muscles hurt. Sprott explained that FMS patients may not be able to distinguish between pain arising from the skin and pain arising from the muscle tissues beneath the skin. Also, the vast majority of findings on FMS point to a dysfunctional pain regulating system that thrives off of noxious inputs to the CNS from the peripheral tissues. The abnormalities in the skin of FMS patients could function as the "food" that keeps this pain state alive.

All of the above findings, funded in part by AFSA, are so amazing that Dr. Sprott has been awarded additional funding to continue his investigations in this area (Part 2). Not only are Sprott's initial findings novel, but the potential for treatments is high given that delta opioid agonists have only recently been developed.

Sprott is performing a number of tests to better understand why the opioid receptors in the tissues are present in abnormally high concentrations in FMS. At the September 2001 MYOPAIN meeting in Portland, OR, Sprott will be presenting both a lecture and a poster abstract to explain the findings just described. Then at the November 2001 ACR meeting in San Francisco, CA, he will present the results of two new findings that were funded in part by AFSA.

As Sprott continues with his investigations in this area, he is keeping an open mind as to the cause of his findings on delta opioid receptors in the skin of FMS patients. It is possible that the receptors may be damaged or flawed, so that the body's endogenous opioids don't work on them properly. Sprott will need a delta agonist to test this hypothesis, but they are not available yet. If the delta opioid receptors are abnormal, Sprott says the next step will be to create a delta-like drug that would fit these receptors to treat FMS patients. This would require more funding, but it can be done!