[intro music]
Host – Dan Keller
Hello, and welcome to Episode Thirty-Two of Multiple Sclerosis Discovery, the podcast of the MS Discovery Forum. I’m your host, Dan Keller.
This week’s podcast features an interview with Dr. David Holtzman of Washington University in St. Louis about how a protein implicated in Alzheimer’s disease may also have a role in MS progression. But to begin, here's a brief summary of some of the latest developments on the MS Discovery Forum at msdiscovery.org.
We recently added a new data visualization to our growing collection. This one organizes every ongoing MS clinical trial—142 of them—into an interactive bubble chart. The size of each bubble represents the sample size of the trial, and the color indicates if the compound has been used to treat MS before. You can organize the chart 10 different ways, including by phase, compound, and sponsor. Go to the “Research Resources” section of our page and click on “data visualizations” to view it.
Yet another Phase 2 trial on autologous hematopoietic stem cell transplant was published last week. We reported on this trial’s results and how it was different from previous trials we covered. Like the last two studies we reported on, this current study yielded very encouraging results. To view all of the stem cell stories, go to the “news and future directions” section of our website and look for any story with an image of a mouse in a little white lab coat.
New research from the journal Neurology suggests that imaging measurements of the spinal cord and retina independently correlate to disability. Specifically, damage in the two structures was related to visual acuity and to the patient’s ability to discern vibration sensation. The authors suggested that clinicians may want to incorporate scans of the spinal cord and retina into their routine practice.
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Now to the interview. Dr. David Holtzman is Chairman of the Department of Neurology at Washington University. He met with MSDF senior science journalist, Carol Cruzan Morton, at a recent Keystone meeting in Taos, New Mexico, to discuss how his work on apolipoprotein Ein Alzheimer's disease may be relevant to MS.
Interviewee – David Holtzman
Most of my career has been focused on trying to understand the pathogenesis of Alzheimer's disease, as well as to develop better diagnostic and treatment methods. However, in doing that – in trying to study the science behind that disease – I've also worked a lot on how normal brain function might be related to not only Alzheimer's disease but just some of the proteins that are involved in both Alzheimer's disease and related disorders.
Interviewer – Carol Cruzan Morton
We're at the Keystone meeting on neuroinflammation in Taos, New Mexico, and at the talk this morning you mentioned that there might be a connection between the ApoE and this protein involved in Alzheimer's and MS. Can you talk a little bit more about how that protein works normally in an Alzheimer's, and how you came to make that connection to multiple sclerosis?
Dr. Holtzman
Sure. Apolipoprotein E first just in terms of a risk factor for Alzheimer's disease ApoE is present as a protein in all of our bodies. It's made in the brain; it's made by the liver; it's at very high levels in the bloodstream. ApoE plays a role in the bloodstream in transporting lipids around the body. It turns out, though, that if the only thing it did was to transport lipids in the blood then you would probably only need to produce it in the liver so that it was secreted into the blood. But interestingly, it's also produced in several other organs: the ovary, the testes, the brain, and a few other places. So in those other organs, it doesn't probably have exactly the same function that it does when it's made by the liver. But the form of the lipoprotein that's in the brain that ApoE is within is somewhat different than it is, for example, in the bloodstream. It's in what's called HDL or high-density lipoproteins in the brain.
MSDF
That's a good thing, right?
Dr. Holtzman
That's the good cholesterol. That's the good cholesterol in the blood. In the brain, it's not entirely clear what these HDL lipoprotein particles are really doing. So, for example, if ApoE is absent from the brain of a person, and there are people that have genetic mutations, they have no ApoE in their body…
MSDF
Completely gone.
Dr. Holtzman
Completely gone. And they have developed serious problems with cholesterol buildup in their arteries because they can't clear big lipoprotein particles from their blood, but their brain is okay, no problem. The people are born normal; brain is okay. And there are probably other proteins in the brain that may be able to takeover for its function in the brain; whereas in the blood that's not the case.
MSDF
And when it goes wrong in Alzheimer's, what's happening…?
Dr. Holtzman
So that's a different issue. So in Alzheimer's disease, there's no lack of ApoE. In humans, there's three different flavors of ApoE: ApoE2, ApoE3, or ApoE4. And there's a very, very subtle difference between the ApoE2, 3, and 4; just really, really small difference. So brain function in people that are of different ApoE types is normal when they're born and when they grow up and as adults. But for some reason – which we'll talk about in a moment – when people have the ApoE4 form of ApoE, it causes a higher risk for Alzheimer's disease probably because it's promoting the buildup of one of the proteins that's really important in causing Alzheimer's disease earlier. So this amyloid protein that builds up in Alzheimer's is strongly influenced by the form of ApoE that you produce. So if you make the E4 form, it's probably because amyloid doesn't get cleared away as well; it builds up earlier. And if you have the ApoE2 form, which is protective against Alzheimer's disease, it pushes out the development of amyloid deposition until very old ages, if ever. That may be something that's related to Alzheimer's disease that's distinct from what it might do in other diseases of the brain like MS, for example.
MSDF
How did you make that connection to MS?
Dr. Holtzman
Right. So over the years, there's been a number of scientists and physicians around the world who have studied the many possible functions of ApoE in the body. And for gosh it's been about 30 years or so, there's been reports that one of the things that ApoE does is to influence inflammatory cells: T cells, macrophages, etc.
MSDF
All over the body or in the brain and spine?
Dr. Holtzman
Yeah, in different locations actually. It's never been completely clear exactly what ApoE is doing to the immune system. A lot of studies individually show effects, but it's not entirely clear what it's doing. And so, I got interested in this personally a few years ago there was a prominent paper published suggesting that one of the things that ApoE does to the immune system outside the brain is to help present antigens to the immune system if they contain lipids. And so, that caught my attention because, one, ApoE carries lipids. And just naively I thought well if it helps present lipid antigens in multiple sclerosis the antigens that are being attacked generally are the lipid related antigens.
MSDF
The myelin.
Dr. Holtzman
The myelin, right, exactly. So I thought well that seems, you know, maybe there's something to this that one could study in relation to MS because of that.
MSDF
And then how did you go about asking those question? Where did you start?
Dr. Holtzman
Basically, I thought alright, well a lot of people who work on MS if they use animal studies use the model EAE. So we thought well some of my colleagues at Washington University have been using the EAE model for years – like many people have – and so we thought well the obvious experiment to try first is just compare animals that express ApoE in their body versus those that don't. And simply ask the question is there anything different about EAE in an animal that lacks ApoE or not? And so, first, we started working with Anne Cross and then later with Greg Wu together who are experts in using animal models of MS. And ultimately published findings showing – and a few other groups have worked on this, as well – showing that there appears to be decreased clinical severity of EAE in a slightly later onset of disease in animals that lack ApoE.
MSDF
And what does that tell you…there might be a role or…?
Dr. Holtzman
Obviously many other studies would need to be done to know if it has a role in human MS. But once we found that, particularly Greg's lab began to ask the question well if that's true what's the mechanism? If there is a mechanism that we could hone in on, is that something that seems logical based on what we actually know about ApoE already? And so, the things that kind of came out of our first series of studies was that – unlike what I initially had thought from this earlier paper – it doesn't appear that ApoE is modifying antigen presentation of cells or the ability of T cells to react against the brain. But something once T cells do get in the brain to attack myelin and other components, there's something about that ApoE is acting on at that point. It could be that it's involved in allowing the myelin to repair, or alternatively it could be that when T cells get into the brain and interact with other cells in the brain – like other immune cells like microglial cells or dendritic cells – that that interaction is altered by ApoE within the brain. That might make sense given that ApoE is highly expressed by macrophages outside the brain, and inside the brain it's highly expressed by what are called activated microglial cells. So kind of the macrophages of the brain. So that's where we kind of are now, and I think there's a lot more studies that could be done to really understand both that interaction as well as whether human ApoE causes the same effect that we saw in animals as mouse ApoE. Because they're not exactly the same; they're similar but not the same.
MSDF
Is there other evidence connecting ApoE or its various forms with MS?
Dr. Holtzman
There are human studies that have been done trying to ask the very simple questions of is the ApoE4, which is a risk factor for Alzheimer's, is that over represented in MS? Or is the ApoE2 form, which is under represented in Alzheimer's, is that protective against MS? And the studies on this some have suggested effects, some haven't. There's no clear answer. But I think if ApoE is involved in MS, it would be less likely to be involved in whether you get MS but more likely involved in the progression of the disease. And I know in the MS field one of the big areas now – now that there's so many studies and as well as treatments that have emerged that are quite effective at suppressing the initial phases of MS, the immune response phases – a lot the work is going into understanding this prolonged progressive phase of MS. And that's where ApoE could be important in sort of the repair and recovery of neurons and axons, for example. Because the fact it transports lipids between cells, maybe it has something to do with recovery of the brain after injury. And that's been speculated on for some time, although not as much work on that has been done in MS.
MSDF
Has it been speculated on in MS or MS and Alzheimer's both or…?
Dr. Holtzman
No, it's been speculated on after a variety of different brain injuries that it plays a role in redistributing lipids in the brain after injury, and that might be promoting recovery. So one possibility that still hasn't really been tested that I'm aware of in models of MS or in human MS is to whether that really happens for ApoE in the human brain or animal models.
MSDF
Can that be tested now?
Dr. Holtzman
Absolutely, absolutely. Those are some of the studies that I think are really critical as the next step.
MSDF
Is it conceivable that the body of knowledge for Alzheimer's research on ApoE might yield a treatment for progressive MS?
Dr. Holtzman
It's possible. I mean a lot of the understanding of what ApoE might be doing in the brain has really expanded because people have been studying Alzheimer's disease and its relationship with ApoE. So I can't imagine it wouldn't help with that because we've learned a lot so far.
MSDF
Are there other treatments in the pipeline for Alzheimer's related to ApoE?
Dr. Holtzman
There are. There's not too many things yet that have reached human trials, but there are groups trying to alter the level of ApoE in the brain or to alter its receptors in the brain as potential treatments for affecting Alzheimer's disease. So yeah, I mean those are the kind of things, as they advance, depending on what's found in regard to the relationship between ApoE and MS could be tried in MS. I don't see why not.
MSDF
That's interesting. What else should I be asking?
Dr. Holtzman
I think what scientifically what I think is really important to still sort out in this area is that when the innate immune cells of the brain – the microglial cells or even macrophages when they get into the brain – they produce tremendous levels of ApoE when that happens. And I think understanding what that protein is really doing in that setting could provide insight into future treatments. So that's what I think is really fascinating to try to understand.
MSDF
Well if it happens in Alzheimer's, as well, it happens before the blood-brain barrier breaks down and then after it, it sounds like.
Dr. Holtzman
Well, in MS, it's probably occurring after there's cell entry into the brain. But the upregulation of ApoE by these innate immune cells is much higher in MS than it is in Alzheimer's disease.
MSDF
Oh, is that right?
Dr. Holtzman
Yeah, yeah.
MSDF
That's interesting. That's even more interesting.
Dr. Holtzman
Yeah, I know. That's why it's really, really fascinating. I think one of the figures from the paper that we published last year from Greg's lab showed that the level of ApoE increasing in microglial cells versus similar cells that are present in the spleen of an animal is like 25 times higher in the setting of an EAE model than normal. So it's really, really high. Is it really doing anything, or is it just a byproduct? I suspect it probably is doing something. So that's what I think would be really interesting to figure out.
MSDF
Thanks. Well I appreciate your taking time out at the Keystone meeting to talk with MS Discovery Forum.
Dr. Holtzman
Yeah, it's great. Well good luck. MS is such a…the treatments that have been evolving are so exciting compared to Alzheimer's disease where we don't yet have good treatments. So I think there will be soon, but I think it's a great opportunity to even advance for ...
MSDF
Is there a chance that the reverse could be true? That treatments existing for MS would be helpful in Alzheimer's?
Dr. Holtzman
That's a good question. I don't know if any of the frequently used ones where you're preventing cell entry into the brain necessarily would be useful for Alzheimer's. But like one of the new drugs, Tecfidera, this oral medication does do some interesting things to cells in the brain that might be useful in a disease like Alzheimer's. So maybe there will be some things that we can translate.
MSDF
I appreciate it. Thank you so much.
Dr. Holtzman
Thank you.
[transition music]
Thank you for listening to Episode Thirty-Two of Multiple Sclerosis Discovery. This podcast was produced by the MS Discovery Forum, MSDF, the premier source of independent news and information on MS research. MSDF’s executive editor is Robert Finn. Msdiscovery.org is part of the non-profit Accelerated Cure Project for Multiple Sclerosis. Robert McBurney is our President and CEO, and Hollie Schmidt is vice president of scientific operations.
Msdiscovery.org aims to focus attention on what is known and not yet known about the causes of MS and related conditions, their pathological mechanisms, and potential ways to intervene. By communicating this information in a way that builds bridges among different disciplines, we hope to open new routes toward significant clinical advances.
We’re interested in your opinions. Please join the discussion on one of our online forums or send comments, criticisms, and suggestions to editor@msdiscovery.org.
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[intro music]
Hello, and welcome to Episode Thirty-One of Multiple Sclerosis Discovery, the podcast of the MS Discovery Forum. I’m your host, Dan Keller.
This week’s podcast features an interview with Dr. Lloyd Kasper about the gut microbiome and its role in MS. But to begin, here is a brief summary of some of the latest developments on the MS Discovery Forum at msdiscovery.org.
Last week our parent organization, the Accelerated Cure Project, launched its latest endeavor called “iConquerMS.” iConquerMS aims to enroll 20,000 people living with MS to play an active role in research, empowering them to securely submit their health data, influence the studies that are carried out by the initiative, and stay informed about the research. Visit iConquerMS.org for more information.
Vision and sensorimotor problems go together in some MS patients. A recent publication in the journal Neurology examined the relationship between MRI measures of the spinal cord and retina in patients with MS. The investigators found some correlation between the two types of metrics, but they also found that damage in each structure had independent relationships with disability. Read the full story in our “news and future directions” section.
And lastly, our previous podcast contained an error. We mentioned a story about a proof-of-concept study of a novel way to monitor lesion repair. However, the story was withheld from publication due to a delay in the release of the research article. The story is now live on our website.
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Now to the interview. Dr. Lloyd Kasper is a faculty member of the Geisel School of Medicine at Dartmouth College. He met with MSDF Executive Editor, Bob Finn, to talk about his research on the gut microbiome and MS.
Interviewer – Robert Finn
Dr. Kasper, welcome.
Interviewee – Lloyd Kasper
Thank you.
MSDF
So to start, why on earth would someone interested in a neurological disease such as MS concern himself with bacteria in the intestines; what’s the connection?
Dr. Kasper
That’s actually a very valid question. And the answer to that question is pretty straightforward, is that there’s a very clear brain-gut access so that the brain talks to the gut primary modulating the physiology of the gut through secretion of a variety of molecules, vasoactive proteins, etc. That in turn affects the motility of the gut. By affecting the motility of the gut, you also affect everything that’s inside the gut, which is – as you mentioned just previously – the 100 trillion bacteria that each and every one of us in this world has. And those bacteria in response to the changes in motility shift their behavior, because these are living organisms, and they secrete a wide range of metabolites.
For the purposes of simplicity, you can look at those metabolites and the effect of those various metabolites on the immune system, taking into account that the gut is the largest immune system in our body – 80% of our immune cells are in the gut. So you’ll have this clear interaction between the brain, its activity physiologically on the gut, and the gut’s activity on the bacteria, and then the bacteria’s activity back on the immune system which leads to issues related to the brain.
MSDF
So you partly answered my next question. There are microbiomes in other places besides the gut – the skin, the urinogenital tract, etc. Do those other microbiomes have any affect or any relationship to multiple sclerosis, do you think?
Dr. Kasper
First of all, the association between the gut microbiome and MS has not yet been fully established, there’s experimental data that would suggest that there is a relationship between the two but that’s still at the experimental level. There really has been very little exploration of the other microbiomes within the body. Remember, the microbiome is not just the microflora. What the microbiome is is the genome of the flora in its relationship to the genome of its host. So when you look at the genomics of MS, for example, in the host – which there’s a lot of work that’s being done – you’re only looking at a fraction of the genetic material that’s involved in this relationship between the gut and the body that it’s in OR any of the other sites that we have microflora – our mouth, as you pointed out; our ears – inside of our ears; our lungs. Those are all areas that bacteria in our body exists in balance with us to achieve a homeostasis. The reason for looking at the gut microbiome is that because it’s the largest, probably the most complex as well.
MSDF
So you focused much of your attention on a single bacterial species. Let me see if I pronounce this correctly – Bacteroides fragilis– am I close?
Dr. Kasper
Correct.
MSDF
And a single substance that it produces, polysaccharide A, or PSA – which has no relation to prostate specific antigen. Why are you focusing on that species and that product?
Dr. Kasper
Well, there is mounting evidence that there are several phyla that colonize the gut. The two major phyla of interest are Firmicutes, which are gram-positive aerobes, and Bacteroides, which are gram-negative anaerobes. I’m talking about at the phyla level over which there is no kingdom, phylum, class, order, family, genus, species. Under each one of those phyla there are many different species. We’ve focused in on primarily Bacteroides because Bacteroides fragilis is a very common commensal that essentially inhabits in the neighborhood of 80-90% of all mankind in the world. Bacteroides as a phyla has been associated with the induction of regulatory T cells. Regulatory T cells live in the colon, in and around the colon, and that’s where Bacteroides live. And it’s been shown that Bacteroides as a phyla have the capacity to drive regulatory T cells.
The reason it’s important in MS is because there is a known deficit in the regulatory T cell population in patients with MS. And we chose Bacteroides fragilis because of all the Bacteroides species, that’s the one that we actually know most about immunologically. There’s at least 20 or 25 years’ worth of very, very important data that shows how this particular molecule, this polysaccharide A – and it’s a polysaccharide, it’s not a peptide, it’s a polysaccharide – how this polysaccharide can drive the immune system to a regulatory phenotype that’s associated with the induction of regulatory T cells, production of IL10, all those factors which are important in MS which we know are deficient in those with MS.
MSDF
When you say drive the immune system, drive T regs, what do you mean by that?
Dr. Kasper
Basically, these bacteria have the capacity to convert effector cells, which would be CD4 positive CD25 negative cells to a regulatory phenotype, which would be CD4 CD25 positive associated with sort of the standard-bearer of regulatory cells, which is Foxp3, which is a nuclear antigen that’s been characterized with it. So this molecule has a remarkable capacity to do that both in vivo and our studies show you can do that actually in vitro as well. So you can take cells that are negative that would be considered naïve or effector-type cells, culture them with this PSA molecule, and convert them to regulatory cells which we know are important in controlling the disease.
MSDF
So remind me whether you want more or fewer of these regulatory T cells.
Dr. Kasper
It depends where you are in life. To give you sort of a circumstantial argument, we know that Firmicutes, which is that other major phyla, has been associated with a number of disease states, including obesity – just to name one – atherosclerosis, but we also know that the Firmicutes have the capacity to drive IL-17. The regulatory T cells are cells that control the IL-17 response, so it’s important to have regulatory T cells to control the IL-17. We know experimentally that IL-17 drives the experimental form of multiple sclerosis EAE, and there is mounting data – and pretty conclusive, I think – MS is probably at least in part driven by IL-17 cells. So you need these regulatory T cells to control that IL-17 response which is probably being driven by the Firmicutes population. And I’m oversimplifying this, because you remember, you’ve got a hundred trillion cells downstairs making god knows how many different metabolites with over a million genes. So what I’m presenting to you is a very simplified version of this remarkably complex organ.
MSDF
So is this leading toward clinical utility for polysaccharide A?
Dr. Kasper
We hope so.
MSDF
Can you tell me more about that?
Dr. Kasper
Well, again, our experimental data – at least in EAE – demonstrates that animals that have been induced with EAE are protected by this polysaccharide. Animals that have EAE, we can therapeutically treat them with this. So this is the first demonstration that a commensal-derived bacterial product that’s within essentially pretty much all of mankind has the capacity to induce regulatory T cells. We don’t know if MS patients are deficient in this or they have the genetic makeup that they can’t respond to it, or whatever it may be. As I said, there’s a real complexity. But the simple observation as we know is that if we take animals that are susceptible to EAE and we treat the prophylactically or therapeutically, we’re able to protect them very, very nicely against the disease process.
And now we have preliminary data in humans that we can take human cells in vitro out of a person and we can drive those human cells from an effector CD4-positive CD25-negative phenotype to a regulatory phenotype by this molecule; just five days of exposure and you see this very nice conversion that’s associated with increased IL10 protection, etc.
MSDF
Do you imagine that the PSA molecule itself, if drug development goes on, is there any chemistry that needs to be done before it might possibly be therapeutic?
Dr. Kasper
A lot of the chemistry has been done. We have a pretty good idea of what the molecule looks like, it’s a repeating polysaccharide chain. And we know what the conditions are at least in animals as far as innate response molecules – TLRs, toll-like receptors, etc. So as far as the molecule itself, I think we have a pretty good understanding. As I said, there’s about 20 years’ worth of very solid biology behind this molecule. So how far we are away from the clinic at this point is a matter of time, resources, and money to be able to move it from the experimental stage that we’re in into the clinic.
MSDF
So you’re not the only research group working on the connection between the gut microbiome and multiple sclerosis. I wonder if you can talk a little bit about how your research fits in with the various other approaches that are going on.
Dr. Kasper
Our research has been focused primarily on immune regulation – how to get the disease under control, at least experimentally and hopefully in MS patients. Most of the other labs are looking primarily at what bacteria or bacteria populations are responsible for affecting the disease; what’s driving the disease. We’ve sort of kept away from that because we were fortunate in being able to find this one molecule derived from a bacteria, as I said, that much of mankind is colonized with, so we’ve been focused mostly on how to regulate the disease rather than what’s driving the disease.
MSDF
Now, as you know, there’s been a lot of talk and controversy about the role of diet in multiple sclerosis. Do you think that gut bacteria and the substances they product may provide that missing link connecting diet with MS.
Dr. Kasper
I think that diet’s going to turn out to be one of the more critical environmental factors that’s associated with the disease process.
MSDF
Can you say a little bit more about that?
Dr. Kasper
Well, if you look at all the risk factors that we know for MS, that being genetics, obesity, smoking, gender – just to name a few – there’s about six or seven of them. Every one of those risk factors is associated with the microbiome. The common denominator for all the risk factors we know so far in MS is the microbiome, and that includes genetics. As I said, the microbiome is a two-way street; it induces things in us and we do things in turn to it, so it’s a binary system. So our speculations – and we just had a paper published in FEBs – Federation of Experimental Biology – is we’re speculating that the gut microbiome is the major environmental risk factor for MS because it includes all of the known risk factors.
So how can you adjust that? Well, the most logical way is diet, right, because it’s the change in the human diet over the last hundred years that may be accountable for the rise in the disease process. It may also be the change in the diet in Africa as well as Asia which were relatively unknown for MS, but now the incidents in Asia as well as in Africa is approaching about the same as it is in the United States and Europe. So as diet has changed, so has the incidence of the disease gone up. So I’m speculating that diet will turn out to be a very important factor in controlling the microflora, which in turn allows for the balance, the homeostasis, in individuals.
MSDF
Well, very interesting. We’ve come to the end of our time, but is there anything you’d like to add, any important questions that I haven’t asked that I should have asked?
Dr. Kasper
No. I think the question about the diet, you know, where do you go from here? Because it’s going to take years and years for scientists and clinicians to sort out what’s actually going on in the microbiome. We’re at the tip of the iceberg in this really, because not only is it the immunology that’s important but it’s the physiology and the physiologic changes that the gut microbiome may be creating in people. So as we get better definition of what activities are going on in the microbiome, the greater the likelihood we’ll have of understanding a whole range of human diseases. And not just MS, but that’s all other autoimmune diseases, cancer, obesity, you know, it’s a long list.
And it may ultimately turn out that it’s a clue to our understanding of cancer, for example, because as the microflora shifts as we grow older – which it does – perhaps what we’re seeing is that early on we have bacteria that induce inflammatory processes – which is why MS is a disease of young people – that tends to peter out as you get older. It’s a well-known thing. It doesn’t go away but it tends to peter out. But that may be parallel to the shift in the microflora that’s going on. So early on in the western diet you’re having mostly Firmicutes. As we get older that shifts to more of Bacteroides, which has more regulation. What does more regulation equal? Well, you’re down-regulating the immune system, and as we get older what do we become susceptible? Cancer. So there’s a real balance that’s going on here. And I think a lot of the clues to human biology as far as disease state are going to ultimately be related to the microbiome.
MSDF
Dr. Kasper, thank you very much.
Dr. Kasper
Thank you.
[transition music]
Thank you for listening to Episode Thirty-One of Multiple Sclerosis Discovery. This podcast was produced by the MS Discovery Forum, MSDF, the premier source of independent news and information on MS research. MSDF’s executive editor is Robert Finn. Msdiscovery.org is part of the non-profit Accelerated Cure Project for Multiple Sclerosis. Robert McBurney is our President and CEO, and Hollie Schmidt is vice president of scientific operations.
Msdiscovery.org aims to focus attention on what is known and not yet known about the causes of MS and related conditions, their pathological mechanisms, and potential ways to intervene. By communicating this information in a way that builds bridges among different disciplines, we hope to open new routes toward significant clinical advances.
We’re interested in your opinions. Please join the discussion on one of our online forums or send comments, criticisms, and suggestions to editor@msdiscovery.org.
[outro music]
[intro music]
Hello, and welcome to Episode Thirty of Multiple Sclerosis Discovery, the podcast of the MS Discovery Forum. I’m your host, Dan Keller.
This week’s podcast features an interview with Dr. Seema Tiwari-Woodruff about estrogen in animal models of MS. But to begin, here’s a brief summary of some of the latest developments on the MS Discovery Forum at msdiscovery.org.
Last week, we reported on the results of another clinical trial for hematopoietic stem cell transplantation in relapsing-remitting MS. Compared to the “halt-MS” trial, which we reported on in January, this study used a less aggressive conditioning approach. Patients involved in the study demonstrated improvement in EDSS scores, and eighty percent of them were relapse-free at four years. The results raised important questions about how to prep MS patients for the transplant. Visit our “News and Future Directions” section to read the full story.
A recent study published in the Multiple Sclerosis Journal demonstrated a potential new way to monitor lesion repair using standard MRI techniques. Clinical trials usually look for new lesions in brain scans to monitor drug efficacy. Lead author, Daniel Reich, told MSDF it’s more important than ever to be able to visualize changes in tissue since drug development is shifting towards neuroprotection and repair.
We’re also pleased to announce that Daniel Reich is one of two new members of our Scientific Advisory Board. Dr. Reich is the director of the Translational Neuroradiology Unit in the National Institute of Neurological Disorders and Stroke, part of NIH. Our other new board member is Deborah Backus, an expert on rehabilitation who is Director of Multiple Sclerosis Research at the Shepherd Center in Atlanta, Georgia. Read their full bios in our “Who We Are” section under the “About Us” tab.
[transition music]
Now to the interview. Dr. Tiwari-Woodruff is an associate professor of biomedical sciences at the University of California, Riverside. She met with MSDF editor-in-chief, Bob Finn, to talk about her research on estrogen and multiple sclerosis.
Interviewer – Robert Finn
Dr. Tiwari-Woodruff, welcome.
Interviewee – Seema Tiwari-Woodruff
Thank you.
MSDF
So what is the connection between estrogen and MS?
Dr. Tiwari-Woodruff
It’s an interesting connection between estrogen and MS, because estrogen is actually a part of life in a way that our brains require it, our bodies require it at every moment of our life, I should say. Many years ago it was found that relapsing-remitting patients had less relapses when they were pregnant, and the causes of that was potentially estrogens – high levels of them – or progesterone or vitamin D. Many researchers went ahead and looked at those high levels of pregnancy estrogens called estriol and found that high levels of estriol were the reason why these women patients had lower levels of MS symptoms.
So eventually down the line, estrogens were parsed out of which estrogen was better. And it turns out that one type of estrogen, which is the estrogen of the alpha, is more immunomodulatory – it actually suppresses the immune response – and that is probably what makes MS symptoms better versus estrogens of the beta ligand was known not to have that much immunomodulatory effect; instead, it was actually directly neuroprotective. So estrogens of the alpha and beta both seem to have an effect on various cell types which are involved in multiple sclerosis.
MSDF
So if estrogen seems to be protective in pregnant women with MS, why not just use estrogen, or an analog like estriol or estradiol, as a treatment?
Dr. Tiwari-Woodruff
That’s a very good question. And, first, these therapies were thought that we were going to use those first, and a lot of clinical trials were going through with that. But what happens with high levels of estrogen is there are two things which are important to know. One is they have a feminizing effect, and the second one is they have a preponderance for causing uterine cancer or breast cancer. So you don’t want to stimulate those two types of cancer. So high levels of estrogen could be dangerous in that aspect. So that is why we don’t want to use that as potential therapy.
MSDF
So you’ve done a lot of work with a specific estrogen receptor agonist called indazole chloride. First, tell me how you came upon this compound.
Dr. Tiwari-Woodruff
So estrogens of the beta ligands are not just being looked at for multiple sclerosis, they were being looked at as a potential therapeutic for menopause – hot flashes included – rheumatoid arthritis, and other impairments like prostate cancer, etc. So there were quite a few chemists who were coming up with various different types of estrogen receptor beta ligands. So while I was doing my work with mouse models of MS in generic estrogen receptor beta ligand, which was the DPN – diarylpropionitrile – a study came out which was actually on indazole chloride which was developed by a chemist, John Katzenellenbogen; he’s done a lot of work on developing these molecules. And this particular compound showed that it decreased activation of astrocytes and microglia; this was published in Cell a few years back. And we met at a meeting, John Katzenellenbogen and myself – we were giving a talk at the same time in a meeting in Stockholm – and we decided to talk to each other. And he said, “Your research is very intriguing on estrogen receptor beta ligand, would you like to try this out?” And that’s how I got my hands on the indazole chloride. And we did some preliminary studies and showed good results. Then we decided to embark on a full-fledged study which was published in PNAS.
MSDF
So you used indazole chloride in two different mouse models of MS, and you used it both prophylactically and in mice that are already showing symptoms. What did you find?
Dr. Tiwari-Woodruff
So prophylactically when you use a compound, you are actually trying to see if you can inhibit the symptoms which are going to come up when you induce a disease, and that is all good. But when you are talking about patients who come to see the doctor, they’re always coming in with symptoms, so they already have the disease ongoing. So the second paradigm where you give the drug when the disease symptoms are already there is closer to what humans are going to be able to see. So the nice thing about indazole chloride was that, prophylactically, definitely it made the mice better, but therapeutically also; they were able to decrease the disease symptoms by nearly 50%.
MSDF
What is the significance of the fact that it seems to work on two different mouse models of MS?
Dr. Tiwari-Woodruff
So when you’re looking at a drug especially in a disease like multiple sclerosis which has two major components – one is inflammatory component and another one is a neurodegenerative component – if you can show that this drug is working in one way or both ways would be very useful for developing better drugs or better treatments. So what we did was when we treated the mice with indazole chloride, in one mouse model which is the experimental autoimmune encephalomyelitis which contains both the inflammatory and the neurodegenerative component, we saw a decrease in the disease symptoms. But we couldn’t tell if the indazole chloride was working in the inflammatory component or the neurodegeneration component, because it showed effect on both.
So we went to a second mouse model which is the toxic cuprizone diet model which doesn’t have a primary inflammatory component. The disease starts with oligodendrocytes, the cells which make the myelin. They die when you feed this diet to the mice, so they have massive demyelination in regions of the brain. When we gave the drug during the remyelination phase, we found that indazole chloride was able to remyelinate the axons better when the drug was present versus when it was absent. So this actually showed us that indazole chloride has two arms to it. One, it inhibits the inflammatory component and the second, it inhibits the neurodegenerative component independent of the inflammatory component.
MSDF
Is it also sort of confirmatory? The EAE is not a perfect model of MS and neither is the cuprizone mouse model, but does it make you feel better that these two completely different models are showing similar effects?
Dr. Tiwari-Woodruff
Absolutely, you really hit the point where… We are always looking for the best model for multiple sclerosis, but because the disease is so complex no one model can be said that it’s 100% mimicking multiple sclerosis. So for us to see that demyelination which occurs both in EAE and the cuprizone model was improved – we actually saw remyelination in both models – really gave us hope that this drug could be directly acting on oligodendrocytes which are forming the myelin, which is the cause of major mode of dysfunction in multiple sclerosis.
MSDF
So does indazole chloride help these mice a little bit, or does it help them a lot?
Dr. Tiwari-Woodruff
So that’s a very good question. Similar to what you might see in the patient population, in the mouse model of MS, especially in the EAE model, the disease is not consistent. So the lesions which appear in the brain of EAE animals are very diverse, unlike the cuprizone model where the demyelination is very consistent. So when you’re looking at these mice, especially in the EAE cohort, if the animal is really, really sick, you actually see the disease symptoms go down just a little bit. But if the animals were sick to the middle level, they actually showed a bigger difference, they showed better recovery. And we hypothesize that the axons which have been injured to the point of no return, if the axons have been demyelinated and injured, it doesn’t matter now when you give them therapeutic drugs, these are not going to improve. So there are certain number of axons in the brain which drop out and we don’t see recovery in those. But said that, overall we still saw a significant increase with indazole chloride treatment in both models.
MSDF
Have you done histology?
Dr. Tiwari-Woodruff
Yes. We’ve done histology, we’ve done electron microscopy. And we do one more thing my lab is very good at, we do electrophysiology. Because one of the things we always think is when you look at remyelination you can see myelin coming up, but is the myelin functional? If the axons can conduct faster or better, then you know that the myelin which has covered the axons is functional. So we do all three. And we also include behavioral testing. So one of the tests we included which a lot of people use is a Rota rod; it’s a motor test to show that the mice can stay on the Rota rod much longer after treatment with indazole versus just the vehicle.
MSDF
Do you see any side effects?
Dr. Tiwari-Woodruff
So that’s interesting. We did not see any side effects in these mice. Agreed, we treated them up to 60 days, we haven’t treated them longer than that, plus we were giving them at a 5 mg/kg/day concentration. So we didn’t see any kind of toxicity. But said that, we still need to do those studies in a thorough way before we can safely say that they had no side effects.
MSDF
So what’s next in the development of indazole chloride as a potential MS treatment?
Dr. Tiwari-Woodruff
So indazole chloride is a good target. And while these studies were going on last year, John Katzenellenbogen and myself, we were talking about how are we going to proceed with this because we were seeing really good results; this is even before I published the paper. And he said what would you like to do? And one of the things we said was is it possible to make better analogs of this compound which are going to be more specific, could be used in a lower concentration and may have a better therapeutic outcome?
So he came up with four analogs which he has sent to me, and we did some preliminary studies to see if they were toxic to cells in culture, because that’s the first thing you do. And they have no toxicity in cells, they actually have shown to behave well with proliferation – depreciation of the cell – and we haven’t seen more cell death or less cell death with them. So we are very excited about that. So coming next month, we are actually going to start treatment of EAE animals, and once that goes through the goal is to do toxicity studies on the two best compounds and see if we can find a company so we can have a backing on these drugs for potential human trials. It’s a couple years from now, at least – it could be even more – but we are actually moving in that direction.
MSDF
Dr. David Baker in a commentary on his multiple sclerosis research blog seemed less than enthusiastic about indazole chloride. He suggested that many compounds seem to work similarly in mouse models. How do you respond to that criticism?
Dr. Tiwari-Woodruff
So Dr. Baker has a very good point on saying that there could be many compounds which are good in EAE but they fizzle out and they don’t go up to clinical trial. I disagree on one point where it comes to indazole chloride, because we have precedence of estrogens showing good therapeutic indication in humans; there were clinical trials done in UCLA where they showed that there was improvement with estriol treatment. And estriol does target both ER-alpha and ER-beta – ER-beta a little more than ER-alpha – so I’m very confident that what we are seeing with estrogen receptor beta is not a fluke. And because it’s a steroid and a small molecule, it does not seem to have a lot of toxicity involved which could be somewhat which is brand new. So we’ll see. I hope Dr. Baker’s wrong and we do manage to get this drug to human patients and we see therapeutic efficacy in them.
MSDF
Dr. Baker also said that a critical experiment had not yet been done. And let me quote from his blog post. He said, “The development of demyelination should be allowed to occur after this damage has abated, then punitive remyelinating drugs should be given.” How do you respond to that?
Dr. Tiwari-Woodruff
Very good point made by Dr. Baker, but I have actually addressed those in the PNAS paper. We part off particularly this aspect of the disease. So the prophylactic treatment was before the disease started; that is what he’s mentioning in the blog. The second part is what is important where EAE disease was induced, and after peak disease had occurred we gave the drug, indazole chloride. At the peak disease, we actually see increased inflammation, but alongside with that we see demyelination and axon degeneration. So the damage has already started. The drug treatment after that is what caused the disease to get better. We saw increased conduction, we saw increased remyelination, and less axon damage.
Similar to that, we also did the experiment in cuprizone. The treatment paradigm was as such: We actually had nine week of demyelination ongoing in the cuprizone model, which is very chronic; it’s chronically ongoing where you have quite a bit of damage of the axons and you have acute demyelination. During the remyelination phases where we gave the drug either to one group and vehicle to the other group, what we saw was that the drug treatment, indazole chloride, actually increased remyelination and decreased axon damage. So I think Dr. Baker was trying to make a point on we haven’t done the right experiment, but I think we have done the right experiment. And further research with indazole chloride will let us know if this is a good drug or not.
MSDF
Dr. Tiwari-Woodruff, is there anything you’d like to add?
Dr. Tiwari-Woodruff
I would like to add one more thing. We have actually looked at indazole chloride in optic neuritis – EAE-induced optic neuritis – and we are going to be publishing a paper fairly soon showing that in optic neuritis we see less inflammation in the retina and increased remyelination in the optic nerve. So I’m very confident that it’s not just a phenomenology in one part of the brain which we picked last time – it was the corpus callosum – that we see increased remyelination and decreased damage caused by EAE with treatment of indazole chloride.
MSDF
Well, thank you very much.
Dr. Tiwari-Woodruff
Thank you.
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Thank you for listening to Episode Thirty of Multiple Sclerosis Discovery. This podcast was produced by the MS Discovery Forum, MSDF, the premier source of independent news and information on MS research. MSDF’s executive editor is Robert Finn. Msdiscovery.org is part of the non-profit Accelerated Cure for Multiple Sclerosis. Robert McBurney is our President and CEO, and Hollie Schmidt is vice president of scientific operations.
Msdiscovery.org aims to focus attention on what is known and not yet known about the causes of MS and related conditions, their pathological mechanisms, and potential ways to intervene. By communicating this information in a way that builds bridges among different disciplines, we hope to open new routes toward significant clinical advances.
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