First Published Jan 7, 2011

Lucia Notterpek Ph.D, leads Florida researchers who are focusing on damaged nerve coating as key to finding a cure for trigeminal neuralgia

Lucia Notterpek and Douglas Anderson at Facial Pain Research Foundation

Board Meeting January 7, 2011

One known culprit behind the piercing, repetitive pain of trigeminal neuralgia is damage to myelin, the waxy coating that insulates nerve fibers against electrical signals that are transmitted from cell to cell. Loss of myelin on the trigeminal nerve causes a short circuit that results in facial pain.To define how myelin defects cause havoc in the nervous system, University of Florida Neuroscience Professor Lucia Notterpek, Ph.D., is leading studies of myelin biology and disease. She is addressing basic questions about healthy myelin, which is vital to the normal rapid movement of electrical impulses through the nerve pathways, and about various nerve disorders, including hereditary demyelinating neuropathies, which result from myelin defects or deficiency. She seeks information that will aid the development of ways to repair or rebuild myelin in order to cure trigeminal neuralgia and other demyelinating diseases.In one project, she is carrying out experiments in mice aimed at defining the role of myelin-producing genes in nerve disease, and in another more clinically oriented study, she is evaluating the effectiveness of various pharmaceutical compounds designed to protect nerves. New and better compounds are urgently needed for trigeminal neuralgia, since all medications currently prescribed for this disorder have side effects ranging from bothersome to intolerable.

“We’re finding genetically altered mice are a very good model for investigating myelin damage,” said Notterpek, who also chairs the Department of Neuroscience at UF’s College of Medicine. “We have a known genetic defect—specifically a deficiency of the peripheral myelin protein 22 gene that is linked to myelin damage. We can induce temporary nerve compression that mimics the condition in classic trigeminal neuralgia, and we can measure sensory response in the animals. Later, after sacrificing the mice, we can analyze the status of the nerves at the molecular level.” Co-investigator, Andrew Ahn, M.D., Ph.D., an assistant professor of neurology, neuroscience and anesthesiology specializing in the treatment of headache and facial pain, has expertise in assessing pain behaviors in mice. By measuring behavioral responses to mildly uncomfortable stimuli such as heat, researchers can detect abnormal pain behaviors in mice in comparison to responses by healthy mice. Ahn said the sensory responses observed and measured in mice cannot be directly equated to human pain, but a series of behavioral approaches aimed at analyzing the animals’ sensitivity to various physical stimuli can be used to approximate various aspects of pain in humans.

Currently, Notterpek seeks to figure out how the PMP22 gene normally works to help produce myelin, and what happens in disease conditions to cause this gene to get stuck in nerve cells rather than traveling to the myelin sheath where it is needed. She refers to this problem as “mistrafficking or abnormal expression of genes, like a traffic jam in part of the nervous system.”

She said daily, repeated observations of mice with known myelin defects reveal a puzzling observation: under the same testing conditions using the same type of stimuli, some of the mice show hypersensitive responses that indicate discomfort, while others show delayed sensory response. In a testing procedure now well-practiced in the UF lab, mice are placed in a clear box while a researcher shines a warm light on their feet, creating a situation similar to walking barefoot on hot sand. The hypersensitive mice move their feet within two to three seconds, while other mice don’t seem to be bothered by the warmness of the light for longer times. The responses of the animals are monitored and recorded by a computer for subsequent analysis. Notterpek said correlating specific gene deficiencies or gene abnormalities to myelin damage and to indications of pain requires long, tedious research that can involve behavioral assessments in hundreds of mice.

In previous studies that resulted in two published papers, she discovered that mice generally have to reach a certain age before they show signs of myelin deterioration—similar to the way TN most often affects people over age 50. Now she and Ahn are investigating how myelin damage in different parts of the nervous system may result in different levels of discomfort. They note, for example, that longer nerves such as those in the hind legs are more susceptible to damage than the shorter nerves.

Notterpek also is testing a hypothesis that the peripheral nerves in mice with PMP22 gene deficiency are more sensitive to injury, and require little provocation to initiate myelin injury. She seeks to determine the least amount of nerve damage needed to trigger loss of myelin in normal mice, and in mice that are deficient in the PMP22 gene. At the close of each study, the mice are sacrificed, and the nerve is removed and examined microscopically to assess the status of the myelin. The researchers also measure the levels of molecules involved in both the myelin sheath pathway and the pain pathway.  

In parallel studies supported by a grant from the National Institutes of Health, the UF team is testing specific nerve-protective compounds—one well established drug and others newly developed. Through a new pilot study, they are beginning to investigate additional commercially available compounds and dietary supplements that may affect the pathways believed to be important to normal myelin formation. They are just starting to test the effects of these compounds on cells that make myelin.

Notterpek’s myelin research is funded in small part by the TNA-Facial Pain Association, which has its national headquarters in Gainesville. She and Ahn currently carry out the TNA-FPA-supported research with one lab technician and the help of non-salaried students on scholarships. They hope to publish the first major manuscript on their findings in 2011.

Although Notterpek has only been at UF for 11 years, her studies of myelin damage and myelin restoration began almost 20 years ago while she served as a research assistant at the Gladstone Institutes of the University of California San Francisco. After entering the doctoral program in neuroscience at UCLA, she completed her thesis on a topic related to multiple sclerosis. She earned her Ph.D. in 1994, followed by a five-year postdoctoral fellowship in neurobiology at Stanford University. Coincidentally about this time, neuroscientists first identified the PMP22 gene and several other genes that play a role in eroding or chipping away myelin from nerves.

While at Stanford, she became involved in a project aimed at determining more precisely how the PMP22 gene may be implicated in myelin injury. When she left Stanford in 1999, she took this project to the University of Florida where she has been working on nerve damage ever since. Her large research program is aimed at translating discoveries in the mice to applications in patients with trigeminal neuralgia and with hereditary demyelinating neuropathies. In both conditions, damage to myelin disrupts the normal transmission of nerve impulses.

Eminent Scholar Douglas K. Anderson, Ph.D., who formerly chaired UF’s Department of Neuroscience and who supports plans for Notterpek’s research, suggests several approaches to myelin repair might be tested in the myelin-deficient mice. One approach would involve patching the demyelinated region of the trigeminal nerve with myelin-producing cells derived from adult or embryonic stem cells, or with the patient’s own Schwann cells, provided these cells do not carry a genetic defect that produces unstable myelin. (Myelin is made up of Schwann cells.)

Anderson also proposes, “Gene therapy might be used to deliver genes that produce endogenous factors known to control pain and/or to knock out genes found to be involved in causing pain. With this approach, it might be possible to manage the pain of TN without actually repairing, or even identifying, the defect producing the pain.”

Anderson is a trustee and scientific advisor for The Facial Pain Research Foundation, who is helping to establish its international consortium of scientists working to cure nerve-generated facial pain. He is internationally known in scientific circles for his development of the first effective medication for acute spinal cord injury and for his pioneering studies of embryonic tissue transplants to halt complicated wounds associated with paralyzing spinal cord injury in people.

Facing My Facial Pain

By Kelsey Zachary

I am often asked about my TN journey and my decision to get brain surgery in an attempt to help manage some of my symptoms. Today, I am exactly 1 year post surgery and while it was the most terrifying thing I have ever done in my life and the recovery was long and challenging, I can say without hesitation that I would do it again tomorrow to have even an ounce of the relief I’ve been lucky to experience with my surgery. 

In early 2011, I woke up to the most excruciating pain I had ever experienced radiating from my ear, across my face and into both my upper and lower jaws. The pain lasted for only a few moments and then disappeared. I got up, surprised and in shock and then it happened again. After a few more episodes, I waddled my way across the street to the walk in clinic. I was lucky to see a doctor who had seen me before. He looked at me and my history, I had an attack. I couldn’t talk through it. When I could talk again I said it felt what I imagined being stabbed in the face or shot in the face would feel like. Right away he said, I’m sending you for a neuro consult, you look like Trigeminal Neuralgia. And my relationship with facial nerve pain began. I’ll spare you the details, but the short of it took me three neurologists before I found one who would listen. The first two said I was too young for any surgical intervention and that drugs were the only logical management of my condition. Armed with angst and bitterness toward a medical system that seemed more content on tranquilizing me with drugs that made me chronically nauseated, dizzy, caused me to gain nearly 70lbs in all, and made me lethargic and exhausted no matter how much I slept, I fought to educate myself about TN and all the options, good and bad. 

I connected with a couple of amazing people who took tearful phone calls from me. They had TN, and they armed me with information and courage to keep pushing. It was a result of those interactions and the uncertainty of the medical support I had that I founded the Trigeminal Neuralgia Lantern Walk of Awareness! It gave the pain a positive meaning and allowed me to connect with other people and hopefully spread some awareness about a disorder that is largely unknown and misunderstood in the medical world. A disease that has the nickname of “the suicide disease” because the percentage of those who attempt suicide because of what TN does to their life. And I would be a hypocrite to say it wasn’t something I thought about. The thing about TN is, above and beyond the pain, it changes how you live. You have triggers that can start a series of rolling electric shock attacks or make it feel your face is on fire or that all of your teeth are being drilled into simultaneously. Many from my support group said that giving birth was easier and less painful than a TN attack. Everyone has different triggers, and they can change over time or depending on how you respond to meds but for most of us, there are a lot of triggers. My triggers included, but definitely were not limited to: eating, especially crunchy textures, anything cold, or too hot. Brushing or flossing my teeth, touch, air moving across my face, smiling too much or too big, talking, laughing, sneezing, blowing my nose, yawning, putting on my glasses, brushing my hair, you get the idea. As you can imagine this can make simple daily tasks quite challenging. I often would have to use a straw if I drank any liquids that were a tiny bit cold. I couldn’t go out with friends or family much because I’d survive work and be in agony by time I got home and exhausted from the pain and meds that all I could do was go to bed and hope I could sleep to try and recover from the day. 

Onto my third neurologist, maxed out of almost all of the pharmaceutical options, and on cocktails of drugs that were starting to cause damage to my liver, I was over 6 years into my TN journey and I had enough. It took away my twenties from me, it took away my ability to spend time with friends and family, it took my away my ability to do things like go hiking or spend time doing photography. I felt drugged up and I was still getting attacks daily. I went back to my neurologist and I fought. He said they couldn’t help me because my mri came back “unremarkable” but thanks to my research and talking to people, I knew two things. MRIs are not always an accurate diagnostic tool for TN, they are a ruling out tool to make sure your TN isn’t caused by things like MS or tumours pressing in the nerves but often the smaller vessels and arteries are hard to identify or are missed entirely. And two, I knew you wanted someone who does a lot of the procedures that you are hoping to get done. After being told I was “unstable” when I came in begging for help again, I finally had my surgical referral and the wait began. 6 weeks went by and I got a call from Dr Anthony Kaufmann’s office in Winnipeg. I pushed for him because I knew the wait would be a year as opposed to up to 8 years in Vancouver. Kaufmann also learned the procedure from the man who invented it and has devoted his entire medical career to cranial nerve disorders. On top of that, I had heard only amazing things about him and his team. There was not an arterial compression on my MRI but the surgeon saw some blood vessels that he thought might be contributing to my attacks. They gave me about a 50% chance at the surgery being successful and I was 100% willing to go try and have it not work because it was better than not trying at this point. I was put on a cancellation list but told it would about 12-14 months to have my microvascular decompression (mvd) surgery. Fast forward 9 months and I was starting to experience some weird pain in other parts of my body and blood tests started to show that my liver function was not working properly anymore from all the medications I was on. I called Winnipeg and next thing I knew I had two weeks to organize my trip there, the time off work and help from family to make it all happen. We arrived with a buffer day to set up our air bnb and then it was off for all my presurgery consults and blood work ups. 

My surgeon spent a long time with me, my husband and mom, answering all of our questions. He also expressed some concerns that some of my symptoms were more typical of atypical Trigeminal Neuralgia or atypical facial pain. These were symptoms that surgery would not have a chance of helping and had I been misdiagnosed previously and actually had an acute form of facial pain, surgery could actually make worse. I was informed that in his opinion it was a 50/50 gamble that surgery would help or make it worse. That was a lot to digest after feeling so sure that surgery was what I wanted. I was 100% willing to try it and have it fail but to try it and have it get worse was not an outcome I had previously considered. I know a handful of people who had previously had other surgical procedures done and had it go incredibly wrong and they ended up worse. I had seen their experience first hand and suddenly everything was more terrifying than I could imagine. I was given a few hours to think it over and ask any other questions and I made the decision to move ahead with surgery. One thing I so appreciated is that Dr. Kaufmann gave me the power by telling me I could say yes now and that I had until the moment they put me under to change my mind. 

The next morning came and despite all the butterflies and anxious nerves, I made it to theatre and after a couple of jokes and a few last minute pre-operative checks I was out. Waking up from surgery was not a great feeling! I had some relatively minor complications that required some extra checks and follow up with the hospital gastroenterologist. I’ve never experienced that much nausea in my life but it only took a minute before they knocked me out with some strong pain killers and the next time I woke up, I was in the neuro step unit being quizzed about where I was, what the day was and what was my name etc. I’ve never been a big fan of hospitals but the nurses and Dr. Kaufmann were amazing. I could press a button or squeak out a noise and a nurse would come and adjust my medication or help me through a nauseous patch. FYI - throwing up, coughing and sneezing post brain surgery are NOT FUN! Staples aren’t exactly the most flexible to sudden, jarring movements. They had me up and walking less than 24 hours after surgery and before I knew it I was released back to to the air bnb until my 2nd follow up with the surgeon. 

In a lot of ways recovery was easier than I anticipated, the electric shocks I would get from my TN were basically gone but I wasn’t prepared for just how tired everything would make me and some of the things I’d have to work on mentally to adjust to being “healthy” when I’ve been used to being “sick” for nearly 8 years. 

I took my first shower and then I slept for half the day. I have fibromyalgia and some of the restrictions to help my head heal caused severe painful flares. To help prevent a CSF (cerebrospinal fluid) in the first several weeks you aren’t allowed to bend over. I was home making pasta one day and spilled sauce on the floor…… I ended up throwing wet paper towel at it and then used my foot to tidy it up. I also had to sleep on a wedge for several weeks. That was probably the most uncomfortable I’ve ever been in a bed! It was worth it though. I healed well and within a few months I was starting to get a little bit of energy back and most of the surgical pain was gone. The TN shocks were also still gone. I am left with what feels like a sunburn on the left side of my face and almost a tickling of the skin that almost never goes away but taking away the awful waves of stabbing, piercing nerve pain has been a total game changer for me. 

It’s been a crazy year and I can hardly believe the transformation. I’ve lost a good chunk of the med induced weight gain, I can go for drinks and dinner and come home tired, but without the searing nerve pain that would stab me relentlessly. I’ve slowly learned to be less cautious and anxious over any little twinge I get in my face - my nerves have comfy little Teflon pillows now! It’s been a huge adjustment to feel good. I still live in chronic pain that never stops and I have bad days and get occasional TN shocks on my non surgical side but for now they are few and far between and don’t seem to have regular triggers or come with the same intensity they did on my other side. For now, I’m just going to milk every moment that I can be relatively normal again. And enjoy every day that I am able to feel good. There’s no cure for TN so while I am doing better now, it is my hope that more will become educated and that we will be able to get help more easily in the future. No one should have to experience the kind of pain that TN causes, even my worst enemy.

Mervyn Rothstein Interviews

Cory R. Nicholas Ph.D.

 

 

Cory R. Nicholas, Ph.D., is a co-founder and chief scientific officer of Neurona Therapeutics. He is also an adjunct assistant professor at the University of California, San Francisco. Before co-founding Neurona, Dr. Nicholas was a faculty member in the Department of Neurology at the University of California, San Francisco, where his research program was focused on investigating the development of human cortical interneurons from their earliest stages to maturity.

Dr. Nicholas pioneered methods to obtain interneuron forerunners from human immature stem cells that were capable of being transplanted into multiple animal models of neurological disease. Neurona was conceived in 2008 to investigate the potential of neuronal cell-based therapy – using such cells as a basis for eliminating neurological pain. Dr. Nicholas and his co-founders, John Rubenstein, M.D., Ph.D., and Arturo Alvarez-Buylla, Ph.D., were among the first to do research that led to the discovery that these cells could potentially inhibit hyper-excitable neural networks in relevant neurological disorders – that the injected interneuron precursor cells became integrated into neural circuitry, possibly allowing for stable repair of the injured nervous system.

The Facial Pain Research Foundation recently agreed to finance a cooperative research project between Neurona and the University of Florida’s McKnight Brain Institute to test the Neurona neuro-stem cells to see if they will stop neuropathic pain in animals. The study should take from 12 to 24 months. If it is successful, Neurona plans to seek Food and Drug Administration approval to begin studies in humans that hopefully will lead to clinical use. 

Dr. Nicholas spoke by telephone from California with Mervyn Rothstein, who was an editor and writer at The New York Times for nearly 30 years before retiring in 2010. Mr. Rothstein has also written for Playbill Magazine, and now playbill.com, since 1991. He currently writes the Stage Directions column for the Playbill web site. He was diagnosed with Trigeminal Neuralgia in 2005. Dr. Nicholas spoke about his research, Neurona, the agreement with the Facial Pain Foundation, and his future hopes.

Why did you decide to focus on pain in your career?

I’m a developmental biologist and I was studying the development of the nervous system, specifically the development of inhibitory nerve cells that are the basis of the collaborative work with the foundation. And we had a colleague at the University of California at San Francisco, Allan Basbaum, who was very interested in seeing if these inhibitory cells could be applied to the treatment of pain, which is his expertise. So our groups joined forces. We were able to work together, and Allan in his laboratory took this and really pioneered application of the cellular transplants that we were studying in the brain and applied them to the spinal cord. And he was able to show that the transplantation of those cells could ameliorate and in some cases completely reverse the experimental pain sensitivities in rodent models of neuropathic pain. 

What is the importance of this Trigeminal Neuralgia research study?

I think this is a tremendous opportunity to take the next step and to build upon the work from Allan and others in our group and really to leverage the resources from the network at the Facial Pain Research Foundation. Because we’ve not yet tried putting these human nerve cells that we think can be restorative and potentially curative into any type of animal model of Trigeminal Neuralgia. One of the reasons we weren’t able to do this on our own is that we didn’t have access to the animal models of this disease. These animal models are quite nuanced and can be difficult to establish on our own. That was when we were introduced by Michael Pasternak of the Foundation to John Neubert at the University of Florida, who had this model. He’s been studying it for a while and had it up and running at his lab. Thankfully Michael Pasternak and the Foundation were able to make that introduction.

How would you describe the work being done at Neurona and its future and its progress?

We submitted a proposal to the Foundation that was just funded where we can do three things. Number one, we can see if the pain phenotype – the observable pain characteristics –  that John has studied for a long time in his animal model can be extended to an animal that does not have an immune system. We need an animal that does not have a functioning immune system to allow for the long-term persistence of the human cells in a rat, because the same kind of immunosuppressants that we will be using in the future, potentially in clinical trial for humans, those drugs don’t always work in rodents. So we had to change the animal strain – so that is the first aim, to see if we can produce a stable pain phenotype using the animal model of Trigeminal Neuralgia that John has studied.

The second aim to see whether our human interneuron cells could be delivered using neurosurgical stereotaxis – a method of locating points within the brain – specifically into the regions where we think the pain triggers are in this disease, and to see if those cells will persist with long-term stability in those rodents.

And then finally, if we succeed with the first two, to see whether the human cells can demonstrate disease-modifying activity and significant compelling pain reduction in this rodent model. If we satisfy all those conditions, then I think we really have considerable support and rationale to pursue a clinical trial in humans for treatment of drug-resistant, intractable Trigeminal Neuralgia. And of course we then have to work with the Food and Drug Administration to run a battery of safety and toxicology studies before doing the first trial. But those would be the next steps.

When do you envision (or hope) that cell-replacement treatments for neuropathic pain (including Trigeminal Neuralgia) will be tested on humans and eventually be ready for use in humans?

The first study, with John, is between one and two years long. And then it would probably be another two to three years of working with the F.D.A. to set up the clinical trial.

What are the biggest obstacles that you face in translating your preclinical findings to the clinic?

That’s a really good question. It’s one that is common not just to pain but just about to any disease, especially in the neurological disease space. And that’s quite simply because rodents are quite different from humans in many aspects. There are different anatomies, different neural circuitries. And especially with pain, where you don’t know how an animal such as a rodent is feeling. We use instead, in lieu of an actual communication as to how a rodent is perceiving pain, we use surrogate experiments to measure aversive behavior or hypersensitivities, in terms of how the animals are moving their limbs or responding to a stimulus. Those surrogates are of course never the same thing as asking a person if they’re experiencing pain. So it’s both the anatomy and the ability to be able to communicate.

On top of this, there are many confounding aspects of pain – psychological, emotional – as well as a very high placebo effect. Which makes all of this very difficult to translate from rodents into humans.

The Facial Pain Research Foundation is moving forward with a sense of urgency to find cures for Trigeminal Neuralgia and related neuropathic pain.  Why have you linked your efforts to such a new organization is the field of pain research?

We were looking for ways to apply this stem-cell technology. First of all, pain was an important potential indication for this kind of cellular transplant. But when we heard from the Foundation the stories of people who are suffering with this disease, it really pulls at your heartstrings and you want to do whatever you can to help.

It just seems like pain is an indication that really does possibly lend itself to testing this proposed cellular therapy. Because it’s a disorder that’s focal in nature – there’s a focus of pain in the facial region that can be targeted, so we have a target to deliver the cells, which is one of the criteria we have for applying the cellular therapy. Because the cells are delivered directly into a lesioned area. They’re not delivered systemically. So when we think about diseases that we can address with this technology we think about a disease that has a well-described focus – an area such as the trigeminal ganglion or other aspects near the brain stem where we think the pain trigger exists in Trigeminal Neuralgia.

This is still quite controversial in the field and nobody knows for sure. So because we don’t understand the cause, it gets back to your question about what makes it difficult to translate to humans. That’s another important aspect as to why this is a tough bridge – because we don’t really know yet what causes this disease. Which is true for many diseases. So we do our best to recapitulate using artificial triggers in rodent models.

Every day many people are contacting the Facial Pain Research Foundation asking if it is truly possible to find a cure for Trigeminal Neuralgia. How would you respond to their questions?

Absolutely I think it’s possible. And I think the Foundation is funding some tremendous work. The Foundation has wisely spent its dollars on leading-edge research to understand the causes of the disease, looking very carefully at human genetics. And complementing this basic understanding with attempts at a cure using gene therapies, and cell therapies like ours. So I think there have been very rationally thought-out efforts to try to cure the disease with the technologies we have and the information we have, along with efforts to understand the causes of the disease.

What keeps you awake at night?

It’s always how do we continue to fund this important research so that we can truly try to make a difference and help people who are suffering from this terrible disease. There are just not enough research dollars available from the National Institutes of Health. There are very few means to acquire dollars for cutting edge moon-shot types of ideas. I think this was a perfect opportunity for the Foundation to connect a couple of different research efforts, one on animal models and the other on stem cell technology, with one another to give  it a shot and see if we can see some efficacy in these animal models. And then if we do, the next step will be trying to figure out how to garner the dollars for the next step, to march this toward the first clinical trial in humans. That’s where it gets very difficult, because the dollar amounts go up. But I think the Foundation has really done a terrific job in seeding these efforts to take that important first step. And if we can determine that this can potentially represent a very effective, long-lasting therapy, possibly a cure, then there’ll be more evidence and rationale and support and enthusiasm for this to snowball. But we’re going to need all the stakeholders to come together on this and continue to raise the dollars to keep this going. And that’s always a source of anxiety – how do we get the dollars to investigate the feasibility part of this, which is what we’re talking about with this first project. But then once we demonstrate feasibility, how do we sustain that, to make this a real human-therapy clinical trial for patients who are suffering. That’s the two-fold anxiety that keeps me up. 

First Report

Fifth Science Meeting At

University Of Florida Orthopaedics & Sports Medicine Institute

Gainesville FL

 Kim Burchiel, M.D., F.A.C.S 

The Facial Pain Research Foundation convened its Fifth Scientific Meeting in Gainesville Florida March 7-8, 2019.  The FPRF has assembled a group of world-class investigators as a consortium to find a cure for Trigeminal Neuralgia.  Clinicians and scientists from the US, England, Canada, and Israel were on site, to lend their perspectives on the state of research on TN.  The agenda was ambitious, but the science and discussions lived up to the promise that we are closing in on the new knowledge that will help us find the cure.  Many new ideas were presented and as is true of high functioning groups, some of the best insights were developed during the dinners and social hours after the formal meeting. 

I will summarize some of the exciting concepts discussed at the scientific sessions, by topic.  I present not so much as a full representation of the work that is currently underway, but as an indication of the high-level science that is being devoted to finding a cure for TN.  The conference commenced with discussions of FPRF funded research, and related investigations, of which I am most familiar.

 Scott Diehl, Ze’ve Seltzer, and Kim Burchiel presented the latest on their project “Genes That Predispose to TN”.

 Kim Burchiel from Oregon Health & Science University discussed new insights into the origins of TN, which relate to different populations of patients with TN. Data is emerging that younger patients, particularly females, develop TN without the requirement for neurovascular compression (NVC) of the nerve.  Older patients do frequently have NVC, and their prognosis from MVD is directly related to the severity of that compression.  The size of the skull compartment that houses the trigeminal nerve (posterior fossa) seems also to be directly related to the incidence of NVC.  This new knowledge will help us direct our genetic search.

Scott Diehl from Rutgers University reviewed the latest analysis of the genetic work on TN. A number of genes are now coming into focus, all of which appear to be relevant to the development, or function, of nerves.  Now that we have identified candidate genes, the next step is to “sequence” these genes to determine if the preliminary findings stand up, and to find the exact mutations in these candidate genes.  The hope is that soon we will be able to determine the function of these genes to either discover or develop new drugs for TN, or even replace defective genes with “gene therapy”. Ze’ve Seltzer from the University of Toronto gave a broad overview of the role of genetics in the development of neuropathic pain, and how findings from his studies on phantom limb pain can provide insights into the genes that predispose to TN. Some preliminary data was presented which suggests that this strategy of comparison of large data sets from patients with neuropathic pain may well provide clues to the origins of TN. 

Allen Basbaum from the University of California, San Francisco discussed his work to identify novel gene targets in pain processing, what he termed the "dark genes.”

Lucia Notterpek from the University of Florida presented her work on dysregulated lipid metabolism as a disease modifier in peripheral neuropathies.

Wolfgang Liedtke from Duke University discussed his work on the Trigeminal nerve root as a rational target for safe and effective treatment of trigeminal nerve pain.

Cory Nichols from Neurona, described the work of his company targeted on developing a human GABAergic interneuron cell therapy to treat refractory epilepsy and neuropathic pain disorders.

The second conference day was devoted to a range of new and innovative potential therapies for TN.

Todd Golde from the University of Florida talked about the possibility of gene therapy for Trigeminal Neuralgia.

Joanna Zakrzewska from the University of London, discussed what happens to our patients with TN over time.

John Neubert from the University of Florida provided an overview of his FPRF project on identifying the neurophysiologic signatures of trigeminal neuralgia pain. 

Mingzhou Ding from the University of Florida related his findings on trigeminal neuralgia and multimodal neuroimaging.

Rob Caudle from the University of Florida presented his findings on a approach to ending neuropathic pain with a combination of substances for blocking pain transmission. A novel and unique approach using old compounds to inhibit neuropathic pain.

Allan Basbaum presented an update on the work of a company he is affiliated with which is working on a genetic “switch” that can potentially selectively turn off pain generation in the trigeminal system, using a benign oral drug.

Mike Iadarola from NIH expanded on the use of a compound to potentially control facial pain and plans to test for ending TN and related neuropathic pain.

Jerry Krbec concluded the day with a discussion on funding opportunities from other sources to support the work of the FPRF.

What I would like to leave you with is the sense of the awe I have for the FPRF, having taken on this mission of finding a cure for TN.  Through hard volunteer work, diligent fund raising, and the assembling of scientific expertise, the FPRF has accomplished something which in my experience is very unique.  The FPRF scientific consortium has become the “place to be” in the neuroscience of TN.  Groundbreaking work is being accomplished, and I came away from this meeting with a sense of optimism that we are close to an understanding of how we may cure TN.  In fact, the most encouraging aspect of this meeting was, to me, how many different avenues of new knowledge are opening up.  I am proud to be part of this work, and am excited to see the next levels of understanding that await!

 Kim Burchiel, M.D., F.A.C.S

Facial Pain Research

Foundation

2018 Research Progress

Compiled and Submitted

April, 2019

By Douglas K. Anderson, Ph.D.

Eminent Scholar Professor and Chair Emeritus Department of Neuroscience

University of Florida College of Medicine

And Director of Research and Trustee

Facial Pain Research Foundation

Trigeminal Neuralgia (TN), is a prime example of neuropathic pain which is pain caused by inmalfunctioning of the nervous system and is considered to be one of the most painful disease conditions known to humans. In addition to the debilitating effects on the lives of those afflicted with neuropathic pain, the cost disorders like TN adds to the U.S. health care system exceeds $100 billion/year. Yet despite the very obvious escalating and pain fueled humanitarian and economic crises, funding targeted at discovering the basic molecular mechanisms underlying neuropathic pain conditions from traditional federal agencies, continues to be inadequate.

The meagerness of funding from these traditional sources has led the growing realization that discovering the root cause of and treatment for TN and other neuropathic pain conditions is going to have to be accomplished with funding from the private sector. To this end, The Facial Pain Research Foundation (FPRF) was created in January, 2011 to provide the critical elements that are necessary and sufficient to study these facial pain conditions. Consequently, the sole mission of the FPRF is “…to establish a well-funded translational (i.e., fundamental discovery to clinical application) research continuum that is dedicated to identifying the mechanisms underlying neuropathic facial pain and to develop novel new therapeutic strategies that will permanently stop the pain of TN and related neuropathic pain syndromes”.

Since its inception a little over eight years ago, the FPRF has raised millions of dollars to support eight separate and distinct research projects. The FPRF uses three fundamental criteria in choosing which proposals are to be considered for funding: (1) the projects are novel and unique; (2) the investigator(s) responsible for each project are among the leading researchers in their respective fields; and (3) there is significant diversification in the research strategies among the projects. It is important to note that these FPRF funds have also served in a multiplier capacity in that some of our investigators have used FPRF support as seed funding to jury to or generate the necessary preliminary data which contributed to these investigators acquiring large grants from the NIH and other foundations and, in some cases, the acquisition of venture capital. Total dollars from other sources that came to our consortium of investigators emanating, all or in part, from FPRF seed funds, is estimated to be somewhere over $40,000,000. The purpose of this yearly update is to briefly summarize these six projects and to highlight the progress that each achieved in 2018.  I have also provided summaries of two new FPRF research projects beginning this Summer 2019.

"Investigating Protein-Lipid Interactions in Peripheral Nerve Myelin"

Lucia Notterpek, Ph.D. (Principal Investigator) Professor and Chair Department of Neuroscience
University of Florida College of Medicine

Progress report (Year 4): May 2018-April 2019

Project 1: Cholesterol homeostasis in peripheral nerve myelin Study staff: Ye Zhou, MS, graduate student

We made excellent progress on this project during the past year, with Ye Zhou the graduate student leading the work in the lab. Because of the great progress, Ye has successfully defended her PhD in March 2019, and will be graduating in May 2019. At the bottom of the progress report, I list publications related to this work that are now in press, or under review.

As described previously in my progress reports, the absence of functional peripheral myelin protein 22 (PMP22) is associated with shortened lifespan in rodents, and severe peripheral nerve myelin abnormalities in several species including humans. Schwann cells and peripheral nerves from PMP22 knockout (KO) mice show deranged cholesterol distribution and aberrant lipid raft morphology, supporting an unrecognized role for PMP22 in cellular lipid metabolism. To examine the mechanisms underlying these abnormalities, we studied Schwann cells and nerves from male and female PMP22 KO mice. Whole-cell current clamp recordings in cultured Schwann cells revealed increased membrane capacitance and decreased membrane resistance in the absence of PMP22, which was consistent with a reduction in membrane cholesterol. Nerves from PMP22-deficient mice contained abnormal lipid droplets, with the levels of proteins involved in cholesterol transport, apolipoprotein E (apoE) and ATP-binding cassette transporter A1 (ABCA1), highly upregulated. Despite the upregulation of ABCA1 and apoE, the absence of PMP22 resulted in reduced localization of the cholesterol transporter at the cell membrane and diminished secretion of apoE-cholesterol. In nerves from normal mice, we identified overlapping distribution of PMP22 and ABCA1 at the Schwann cell plasma membrane. Together, these results reveal a novel role for PMP22 in regulating lipid metabolism and cholesterol trafficking through functional interaction with the cholesterol efflux regulatory protein, ABCA1.

Significance of the described results (lay terms):
Understanding the subcellular events that underlie abnormal myelin formation is critical for advancing therapy development for neuropathies. PMP22 is an essential peripheral myelin protein, as its genetic abnormalities account for approximately 80% of hereditary neuropathies. Here we demonstrated that in the absence of PMP22, the cellular and electrophysiological properties of the Schwann cells plasma membrane are altered, and cholesterol trafficking and lipid homeostasis are perturbed. The molecular mechanisms for these abnormalities involve a functional interplay between PMP22, cholesterol, apoE and the major cholesterol-efflux transporter protein ABCA1. These findings establish a critical role for PMP22 in the maintenance of cholesterol homeostasis in peripheral nerves and provide new knowledge for efforts toward therapy development.

 Project 2: Cholesterol homeostasis in peripheral nerve myelin, with a focus on statins Year 12: May 2018-April 2019

Mohammed Al Salihi, MD, PhD, postdoctoral fellow was the key investigator on this project, but he resigned in March 2019, and returned to training in medicine. I will be hiring a new person shortly.

Statins are lipid-lowering agents that are used in the treatment of dyslipidemia by the inhibition of the HMG-CoA reductase enzyme, which is the rate-limiting step in cellular cholesterol biosynthesis. The influence of statins on the nervous system is controversial, particularly concerning peripheral nerves. Currently it is debated whether statins alleviate or aggravate neuropathic pain, and/or whether they cause the neuropathic pain. Based on our investigations of lipid metabolism in peripheral nerves, and these mentioned clinical observations, we hypothesize that in certain individuals, statins alter the stability of myelin making it susceptible to localized compression-induced demyelination with a subsequent painful neuropathy. Dr. Al Salihi has been testing the effects of statins on Schwann cells and on myelination of neurites in vitro, and has found that statins lead to myelin fragmentation. With Mohammed leaving the lab, we are now repeating these results and expanding the studies to more in depth analyses of myelin and Schwann cells viability. Related to the statin project, Ye is exploring the influence of exogenous cholesterol supplementation on myelinating cultures from heterozygous PMP22 knock out mice, which model compression-induced neuropathy. Quantification of internodal myelin segments and internode numbers indicate beneficial influence of cholesterol supplementation. Together, these studies will help us unravel how intracellularly made cholesterol and exogenously supplied cholesterol impact Schwann cell biology, specifically myelin formation and stability.
In a related project, we examined the influence of a neutral lipid-enriched diet on myelination in neuropathic mice. For our studies we used Trembler J (TrJ) mice that carry a spontaneous mutation in peripheral myelin protein 22 (PMP22) and model early-onset, severe neuropathy. While it is known that lipid metabolism is critical for myelination and myelin maintenance, the impact of a cholesterol-enriched diet on early-onset neuropathies has not been examined. Furthermore, the mechanisms by which dietary lipid supplementation and/or substitution (no increase in overall calorie intake) benefit nerve myelin are unclear. To address these questions, we examined the lipid profile of peripheral nerves from 6-month old TrJ mice and tested the impact of a 6-week long neutral lipid-enriched high-fat diet (HFD) on neuropathy progression in young, newly-weaned mice. Oil Red O staining showed pronounced neutral lipid accumulation in nerves from affected, neuropathic mice, along with elevated levels of key cholesterol and triglyceride transport proteins including apoE, LRP1 and ABCA1, compared with wild type (Wt). In young mice, the short-term HFD intervention increased serum cholesterol levels, without impacting triglycerides, or body and liver weights. Nerves from neuropathic TrJ mice showed improvements in the maintenance of myelinated fibers after the 6-week long dietary intervention. Concomitantly, aberrant Schwann cell proliferation was attenuated, as detected by reduction in mitotic markers and in c-Jun expression. Nerves from HFD fed TrJ mice also contained fewer macrophages, with a normalized count of inflammatory CD11b+ cells. In addition, we detected an increase in neutral lipids in the nerve endoneurium and a trend toward normalization of apoE, LRP1, and ABCA1 expression, after the HFD feeding. Together, these results demonstrate a beneficial influence of a neutral lipid-enriched diet on neuropathy progression in young TrJ mice, and support further work in investigating the potential benefits of dietary lipids on demyelinating neuropathies. In our next set of studies, we plan to further optimize the lipid-enriched diet and examine sensory deficits in the various neuropathic models, with and without dietary intervention.

Related to these studies we have the following manuscripts at various stages of publication:
1. Zhou Y, Lee S, Bazick, H, Miles J, Tavori H, Landreth GE, Fazio S, , Notterpek L. PMP22 regulates cholesterol trafficking and ABCA1-mediated cholesterol efflux. J Neuroscience, 2019 (in press).
2. Zhou Y, Lee S, Bazick, H, Miles J, Fethiere A, AISalihi M, Tavori H, Fazio S, , Notterpek L. “A neutral lipid-enriched diet improves myelination and alleviates peripheral nerve pathology in neuropathic mice. Experimental Neurology (under review)
3. Zhou Y, et al., Steatosis and cholesterol mislocalization in the liver of PMP22-deficient mice (In preparation for Journal of Lipid Research)
4. Zhou Y, et al., PMP22 senses cellular cholesterol homeostasis and regulates cholesterol subcellular trafficking via CRAC domain(In preparation for Cellular Neuroscience)
5. AlSalihi, Bazick et al., HMG-CoA reductase inhibitors and their effect on Rat Schwann cells and myelination (In preparation but still collecting data)

"Mapping Towards a Cure: Identification of Neurophysiologic Signatures of Trigeminal Neuralgia Pain"

Summary:

A University of Florida (UF) team consisting of John K, Neubert, D.D.S.,Ph.D. (Project Leader), Mingzhou Ding, Ph.D., Robert Caudle, Ph.D., Marcelo Febo, Ph.D., and Todd Golde, M.D., Ph.D. are investigating the neurophysiological signature of trigeminal neuralgia (TN) pain and developing promising new therapies. This group represents expertise in facial pain, structural and functional neuroimaging, neurophysiology, molecular biology, pharmacology, and viral vectors. Initially, this project was developed to include both preclinical animal models of trigeminal nerve pain and human studies using imaging studies from TN subjects to investigate the cause of TN. The preclinical animal studies have yielded the novel therapeutic agent, CGRP-Botox (see Dr. Caudle’s separate report). Dr. Febo has provided additional animal imaging analyses and has identified unique connections within the brain following trigeminal nerve injury. These findings confirm unique pathways relevant to trigeminal nerve pain and can provide a foundation for studying humans using the same imaging analyses. The human studies have found critical brain regions important in transmitting pain in TN patients and we identified an exciting relationship relating to neuroinflammation, chronicity, and surgery (see below in Human Studies). These findings provide the foundation for the journal article that is in preparation and will be submitted in the next few months. We have made significant progress towards completing the goals of this project and will expand on these exciting results (see Future Directions) to provide a pathway for finding a cure for TN.

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