[intro music]
Host – Dan Keller
Hello, and welcome to Episode Ninety-six of Multiple Sclerosis Discovery, the podcast of the MS Discovery Forum. I’m Dan Keller.
Today's interview features Drs. Bibiana Bielekova, who is an investigator at the National Institutes of Health, and Mika Komori, a postdoctoral fellow in her lab. We caught up with the two physician-researchers at the ACTRIMS meeting in New Orleans earlier this year. At the meeting, Dr. Komori talked about a new and more sensitive way to evaluate what may be happening in the brains and spinal cords of people with progressive MS.
In a recent study, she examined samples of cerebral spinal fluid, or CSF, collected through a thin needle near the base of the spine. She was scouting for immunological biomarkers of progressive MS. In the analysis, a molecule called CD27, mostly from T cells, stood out, as did another marker specific to B cells. Even more revealing was the ratio of the CD27 molecule to the T cells. T cells are a big player in relapsing MS and not usually associated with the progressive, more neurodegenerative forms of MS. The unexpected results raise new questions about why immune-modulating drugs do not seem to be effective against progressive MS.
If validated, the new test may lead to better diagnosis and treatment of people with MS and other neurological disorders. And it may speed up clinical trials in progressive MS and reduce their cost. In fact, the same research team used their new biomarker test in a small phase 2 study of the anti-B cell drug, rituximab, delivered both intravenously in the blood and intrathecally in the spinal column. Unfortunately, the new biomarker test showed that the double delivery system did not work as expected to eliminate inflammatory B cells trapped in the brains of people with progressive MS. They stopped the study early for lack of efficacy.
In a change to our usual podcast format, Dr. Bielekova interviewed Dr. Komori about the specifics of the study and put the results in a larger context. Midway through the interview, Carol Morton, a past editor of MS Discovery Forum, asked both doctor-scientists about what the new test means for treating patients.
Interviewer – Dr. Bibiana Bielekova
As a physician, when we see patients, we don’t really know what’s happening in their brains, right? We are using some tools that are supposed to help us to identify like, for example, MRI, but they are not perfect. So, how did you choose to address that problem?
Interviewee – Dr. Mika Komori
So, when I saw patients, I can’t tell them that the drug, which are now available, is effective or not, especially for progressive MS patients, because currently so far all big clinical trials, they didn’t show any effects on them. Because of that result, we think progressive MS patients don’t have any intrathecal inflammation. So far we believe MS – multiple sclerosis – is inflammatory disease, but we don’t know if it’s true for progressive MS or not.
Dr. Bielekova
Yes, and, in fact, it is because these tools are not that ideal, right? So, in fact, by using the tools that are available, such as MRI or these cerebrospinal fluid markers that have been developed more than 40 years ago, the conclusion is that there isn’t inflammation in progressive MS, right, because all of them are basically decreased, with exception of IgG index which, as you said, remains stable for many, many years. So somebody who had, for example, infection during childhood can have elevated IgG index for the rest of their life.
So that was really the reason why we wanted to develop something that is more sensitive. And also, I think, the question really was, does cerebrospinal fluid reflect what’s happening in the brain tissue? And can we somehow develop technology that can tell us what is happening in the brain tissue without taking, of course, the biopsy, which is extremely invasive, and we cannot really use it in people, right? So how did you address that problem?
Dr. Komori
We developed a very good way to measure soluble biomarkers in the CSF with a new technique called Meso Scale Discovery.
Dr. Bielekova
So I think we should probably step back a little bit and say that our goal was to really look at the biomarkers that can point towards a specific cell, right? Because there are proteins that can be released by all immune cells, such as for example, chemokines, and, in fact, the vast majority of cytokines. But we were especially interested in looking at the proteins than can specifically point to one particular cell type, and so you did something else to really measure that, right? In fact, we all helped you to do that because it was so difficult, right? So we employed the whole lab to do the separation of cells. And then you were looking at which cells are producing these biomarkers.
Dr. Komori
Right.
Dr. Bielekova
So tell us about those three that really panned out as the best.
Dr. Komori
When we see the results of soluble CD27, soluble CD14, and soluble CD21, soluble CD27 correctly identified all inflammatory neurological disease and also only negative for noninflammatory neurological disease patients.
Dr. Bielekova
Whereas all of the traditional markers together, if we put all of them together, they could identify only about two-thirds of the patients. We were really surprised, because – I mean, the field believed, as Mika had said, right, based on the fact you no longer have contrast-enhancing lesions; the treatments no longer work; you don’t have clear cytosis, meaning a large number of white blood cells in the cerebrospinal fluid – the field and us, we believed that what we are going to see, once Mika unblinds these two cohorts of close to 200 patients each that we will see that progressive patients have significantly lower amount of inflammation. But that’s not what she saw. She saw something completely different and surprising. So what did you see?
Dr. Komori
Well we saw almost comparable level of intrathecal inflammation in both PPMS/SPMS to RRMS.
Dr. Bielekova
Not almost, right? There wasn’t any statistically significant difference.
Dr. Komori
No.
Dr. Bielekova
So on the group level, we saw the same level.
Dr. Komori
Absolutely. Yes, and it was so significant compared to a healthy donor and noninflammatory neurological diseases. So all healthy donor and neuro-inflammatory neurological diseases, they didn’t have high level of especially soluble CD27. But almost 90% of each MS subtypes had very high soluble CD27.
Dr. Bielekova
But when you did the ratios…
Dr. Komori
Then we did the ratio and calculated soluble CD27 per T cell in CSF. We found that even higher level of ratio results in progressive MS patients, both in primary progressive and secondary progressive. And for our MS patients the ratio is almost comparable to healthy donor and noninflammatory neurological diseases. That means, although we don’t see many immune cells in the CSF for progressive MS patients, those cells are in the CNS tissue. And it cannot move, but just shedding the soluble markers like soluble CD27 into the CSF. And we can detect that marker when we measure the CSF.
Dr. Bielekova
And I think it really nicely ties with the beautiful pathology studies that have been published that demonstrate that patients with progressive MS no longer have this very dense inflammation around the vessel, which is the type inflammation that is capable of opening blood-brain barrier, right? Which means that that’s the type of inflammation that is associated with contrast-enhancing lesions. But instead, when pathologists looked at normal-appearing white matter, they could see, you know, one T cell here, one T cell there, right? It’s really difficult to quantify it on the pathology level, because they never assay the whole brain. But your assay is, in fact, looking at the entire brain. And what your assay is saying is that the number of cells is basically the same in all of these different stages of MS disease process. What is really different is where they are located, right?
So, in relapsing/remitting MS, they are located in the perivascular aggregates, not much in the normal appearing white matter. That’s where they open the blood-brain barrier. But in the progressive MS they are located in the brain. And I think our conclusion was that, in fact, this may be the major reason why current treatments are not working for progressive MS, because basically we would expect that only those drugs can work in progressive MS that have very good penetrance into the brain tissue.
Now, I think that we also have to realize that just the presence of the cells in the tissue doesn’t tell us that they are pathogenic, right? So it may be that they are there, but something else is driving disability. But on the other hand, the data we have, for example, from recently announced ocrelizumab trial is really suggesting that these cells are indeed pathogenic, right? So I think that we can say that progressive MS is neurodegenerative disease only if we can eliminate inflammation from the brain of progressive MS patients, and it does not translate into stopping disability or significantly inhibiting disability.
But the data that we have published, and we are still collecting, are really suggesting that current treatments, in fact, do not eliminate cells from the brain of progressive MS patients, right? So I think the question of compartmentalized inflammation versus neurodegeneration in progressive MS is really open. And I mean my view is that probably both of them are going to be important, right? I think that just because there are immune cells in the CNS tissue, it doesn’t necessarily mean that neurodegeneration is also not present. But I think the hypothesis that progressive MS is no longer inflammatory disease, and it’s pure neurodegenerative disease – I think that hypothesis is, at the moment, not confirmed, right, because we don’t have the experiment where we would eliminate the inflammation.
MSDF
So both of you are physicians. Does this influence how you would treat people with progressive MS at all?
Dr. Komori
Yes, absolutely. So from now, when I see high ratio results of progressive MS patients – soluble CD27 per T cell – if they have high ratio, then I will not treat them with current immunomodulatory drugs. But may be a good idea to try more effective drugs to penetrate in the brain. But if the progressive MS patients, although they have high soluble CD27 but low ratio results, then it will be worthwhile to use some immunomodulatory drugs for them.
Dr. Bielekova
I would even kind of take a step back and say that in order to be able to use your tool for the treatment decision, I think we need to gain another type of knowledge which we don’t have yet and that is what are current treatments really doing on these type of assays and this type of pathology, right? So we really need to quantify each individual drug, how much it can affect intrathecal inflammation in patients with the open blood-brain barrier, where the drug actually can get into the tissue versus patients with closed blood-brain barrier, where potentially the penetrance is much, much, much more limited, right. I think that it brings back that case that I mentioned where, you know, we are using, for example, cyclophosphamide, and we are assuming that just because the drug is inhibiting immune response in the blood, it will inhibit immune response in the cerebrospinal fluid. And I think that those assumptions are just not tested, right? And, in fact, when we tested them, we realized that the effect on the intrathecal inflammation is extremely limited.
So I think that there is a knowledge that we need to gain, which is this knowledge of which MS drug is doing what. And, if we conclude that they are not doing a sufficient job, which I am afraid that’s going to be the conclusion, then we can use this technology to in fact develop new drugs, right? Because your technology is looking at the type of inflammation that cannot be measured by contrast-enhancing lesions. In fact cannot be measured by anything that we have available thus far, right? So how are we going to even try to develop new drugs for progressive MS?
Well, we can do it by doing large, Phase 3 trials like we have been doing thus far and looking at disability. But of course, that’s incredibly expensive, and it’s just very inefficient way to do it. So instead, doing small trials where you take patients because they have intrathecal inflammation, right. So you now measure; (A) how much inflammation; and (B) its compartmentalized inflammation. Then you can give them the drug, and then you say, ‘okay so now I’m going to measure’ – and you can do it in 3 months or 6 months, in much, much, much shorter time periods – and say, you know, ‘how much is this drug inhibiting intrathecal inflammation?’ And, in fact, that’s precisely what you have done in our RIVITALISE trial, right? Which, unfortunately, we stopped precisely because your assays determined that we are not achieving as much inhibition of inflammation as we were hoping to achieve. So I think that that makes drug development very efficient. And hopefully it will allow us as a society, to screen many, many more treatments on a yearly basis than what we can do currently.
Dr. Komori
I think if we can measure the cell-specific or pathophysiology-specific biomarkers, we can combine treatments.
Dr. Bielekova
Absolutely.
Dr. Komori
If, like interferon, it doesn’t work, let’s try natalizumab. If not, let’s try this, but if we know that interferon works for this side of the pathophysiology, but natalizumab works for this side of the pathophysiology, then we can combine them to more effective treatment.
Dr. Bielekova
Yes, and I think that I would say ‘more to come,’ right? So far Mika published data that relate to inflammation, but the lab is working very hard on biomarkers that reflect, for example, mitochondrial dysfunction, or neurodegenerative processes. And we absolutely believe that treatments will have to be combined, and that this, you know, basically assaying cerebrospinal fluid is going to be that tool that will, on one hand allow us to develop these new treatments, and on the other hand, allow us to treat patients smartly at the bedside.
[transition music]
MSDF
Thank you for listening to Episode Ninety-six 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. Msdiscovery.org is part of the nonprofit 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.
[outro music]
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.
For Multiple Sclerosis Discovery, I'm Dan Keller.
[intro music]
Host – Dan Keller
Hello, and welcome to Episode Ninety-five of Multiple Sclerosis Discovery, the podcast of the MS Discovery Forum. I’m Dan Keller.
Today's interview features Dr. Michael Levy, associate professor of neurology at Johns Hopkins University. When we met in his office, he told me about his work on the role of T cells in neuromyelitis optica, or NMO. Finding antibodies to aquaporin-4 is indicative of NMO. But when Dr. Levy used aquaporin-4 reactive T cells, they could induce NMO in a mouse model, giving a clue to the role of T cells in the disease, and possibly opening up a new therapeutic avenue.
Interviewer – Dan Keller
What's different about this approach than what has been thought of previously?
Interviewee – Michael Levy
In neuromyelitis optica, there is the thought that the disease involves an antibody, the anti-aquaporin-4 antibody, that that antibody is involved in causing the disease. And what we demonstrated in this model is that we could recreate the disease simply by developing T cells against aquaporin-4. It's the exact same target as the antibody, but instead of using the antibody to exacerbate disease, we use T cells. And it works really well and causes optic neuritis and transverse myelitis, just like in the patient.
MSDF
Can you briefly describe your method?
Dr. Levy
We raised T cells in mice that don't have aquaporin-4. These mice see aquaporin-4 as a foreign antigen and mount an aggressive immune response against them, and we harvest those T cells from that animal. And what we do is we polarize them. We basically turn them into more aggressive types of immune cells in a dish. And then we transfer those T cells to a naïve mouse that does contain aquaporin-4. And those T cells attack the aquaporin-4, and it does so only in the optic nerves and the spinal cord and also a little bit in the brain.
MSDF
But aquaporin-4 is distributed more widely than that in the body.
Dr. Levy
That's correct. Actually, there's a higher level of aquaporin-4 in the lung, stomach, kidneys, muscle. Many tissues contain aquaporin-4, but the T cells decide which aquaporin-4 to attack. They are a thoughtful type of cell, and for whatever reason, and this is true in the human, too, the T cells only decide to go for those specific tissues.
MSDF
How does a mouse with aquaporin-4 get to an age where you can actually get these T cells out of it? What's the use of aquaporin-4 if they really can survive without it?
Dr. Levy
It's amazing that these knockout mice, they don't have any aquaporin-4, are completely viable. There are some abnormalities in function under certain stressful conditions, like stroke or brain trauma, but for the most part, they live normal lives. They must have a good compensatory mechanism that they don't need aquaporin-4, and that's fortunate for us because we can create these animal models.
MSDF
When you transferred these T cells to wild-type mice, what did you see?
Dr. Levy
Eight days after the transfer, the first thing we noticed is that the mice started blinking and the eyes became sunken into the head, and that's a sign of severe optic neuritis. And then two days later, they had a dragging tail. And a day after that, their hind limbs were paralyzed, and that indicated transverse myelitis.
MSDF
What's the role of the antibody if you can induce the disease with the T cell? And does the antibody in itself without T cells have an effect?
Dr. Levy
We looked at that, and what we found is that the antibody by itself has absolutely no effect. But in the context of a T cell attack, it can exacerbate the disease, and it does lend specificity to the pathology when you look at it under a microscope. If you add the antibody, there is more aquaporin-4 damage, and it recruits compliment, which causes that damage. So that's really the role of the antibody.
MSDF
Can you induce the antibody without T cells? Essentially is aquaporin-4 a T-dependent antigen?
Dr. Levy
We think it is, and that's based on the type of antibody it is. The antibody in a human is what's called an IgG1 subtype, which is a T cell-dependent subtype. And that bears out in the animal models as well.
MSDF
So the antibody is really an enhancer in the disease as opposed to an initiator?
Dr. Levy
That's our thinking. It's not just an enhancer, but also a biomarker of the disease. And maybe in some patients, the antibody is not as harmful, but more of just a biomarker.
MSDF
What's the significance of these findings, especially as it relates to human conditions?
Dr. Levy
We're always looking for a new target to treat NMO patients, and there were some who were thinking that we should be targeting the antibody to try to either remove it or soak it up somehow. And maybe our model suggests that we should be targeting the T cells. And if there were ways that we could retrain or reeducate those T cells not to attack aquaporin-4 and create a really specific therapy, then we could avoid these broader immunosuppressive therapies that are necessary now to treat these patients.
MSDF
Since you have a defined antigen in this case, and I assume you can make some of it, do you have any hope of being able to induce high-zone tolerance using it?
Dr. Levy
That is our goal, and we've partnered with a company now to try to create a vaccine therapy using that antigen target. Again, in the same way that a T cell is turned pathogenic with this antigen, we can then retrain that T cell to be tolerized to it. And so we're hoping to apply that sort of technology to humans.
MSDF
Now you're coming in at a late stage of the disease. I mean, someone has to present with the disease for you to want to treat it. So really, you can't prevent it. This would be a therapeutic vaccine, not a preventative vaccine?
Dr. Levy
Correct. A vaccine therapy more along the lines of retraining than preventing and preparing. Correct.
MSDF
Now this applies to NMO, but what about applying it to MS? With NMO, you've got a defined antigen.
Dr. Levy
That's exactly right. And with NMO, there isn't what we call antigen spreading, which is where the immune system decides instead of targeting that one antigen, it's going to spread. The epitope is going to spread to other areas of myelin and maybe other components of the central nervous system. With NMO, the antigen is really focused on aquaporin-4, and so that's our advantage. And in MS, there are a lot more targets, and it's probably more of a heterogeneous disease. It would be harder to develop a vaccine therapy for MS.
MSDF
Where do you go from here? What's next?
Dr. Levy
Next is demonstrating that the mouse model responds to a vaccine therapy approach. We'd like to show that the T cells can be stopped, even when they're pathogenically targeting the aquaporin-4. Transferred into a mouse, we need to demonstrate that a vaccine therapy can prevent their attacks.
MSDF
Have you looked or demonstrated T cell receptors specifically for aquaporin-4 fragments?
Dr. Levy
We're looking at that now. We're looking in human subjects. We isolate their T cells, and we're looking for a response to certain epitopes of aquaporin-4. That has been done by other groups, but we're looking for specifically pathogenic epitopes now.
MSDF
Is there any thought towards some sort of suicide experiment where these T cells that have become activated could then be killed because they're proliferating?
Dr. Levy
There is a company in Houston called Opexa Therapeutics. They're doing something similar to that. They're picking out patients' T cells that are reactive against aquaporin-4 and inducing apoptosis so that when these T cells are reintroduced to the body, there is a tolerization. So it is kind of the same thing that you're suggesting. And they are hoping to launch a trial like this by next year.
MSDF
Is there anything we've missed or important to add?
Dr. Levy
What I'd like to emphasize again is that by focusing on the T cells, we can really hone in on the very upstream early event and really specifically treat…I don't want to use the C word to say cure, but it's really focusing on the source of the problem, rather than treating all the downstream consequences, which is what we do now. So I think our approach has that specific advantage.
MSDF
An advantage over a more global nonspecific immunosuppression?
Dr. Levy
Exactly, which is what we're doing now.
MSDF
Very good. Thanks.
Dr. Levy
Thank you.
[transition music]
MSDF
Thank you for listening to Episode Ninety-five 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. Msdiscovery.org is part of the nonprofit 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.
[outro music]
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.
For Multiple Sclerosis Discovery, I'm Dan Keller.
[intro music]
Host – Dan Keller
Hello, and welcome to Episode Ninety-four of Multiple Sclerosis Discovery, the podcast of the MS Discovery Forum. I’m Dan Keller.
Today's interview features Dr. Oscar Fernandez, a senior investigator at the Málaga Regional University Hospital in Málaga, Spain. When we met at a neurology conference in Chile, he reviewed for me some of the elements of risk stratification for second-line therapies for MS. That implies there are first-line therapies and probably third-line ones, as well – terms that Dr. Fernandez is not particularly fond of.
Interviewee – Oscar Fernandez
I am very much against that classification, but this is being used for clinicians, so I have to accept that. I believe that there is one drug for one patient, and I don't believe in lines. Because if you use lines, then you must be forced sometimes to do the passing through all these lines. And many times you must go indirectly from the very beginning to second or third line and the case is very severe. Anyhow, lines have been defined more or less just taking into account the benefit and the risk. And first line are those drug who are not terrible beneficial; they have more this efficacy, but they are very safe in the long term. This is the first line, and those are interferons, there are like four interferons so far, and glatiramer acetate, this is first line. And second line are those drug where are more efficacious but more risky also. So there you have natalizumab, fingolimod, alemtuzumab, and mitoxantrone.
And even you can go further for the third line, which is maybe bone marrow transplantation and some experimental therapies by now. There are many new drugs coming, and then we must try to classify these as first, second, or third lines. It's very difficult for clinicians today to image, for instance, ocrelizumab, which drug is that? Is it first, second, or third line? Is it very efficacious, is it very safe until now? So why it should be classified as second line? Probably the agencies will say this is for active relapsing or for active MS and just let the clinicians to use it properly.
Interviewer – Dan Keller
So what goes into the risk stratification? What parameters do you consider?
Dr. Fernandez
Yeah, the first thing is that most clinicians use a balance, for the balance of efficacy and safety. But then they put numbers. You must put numbers. I mean the numbers are there. I mean for low-risk drugs and for very mild diseases the number is 1 in 10,000. You can have severe adverse events 1 in 10,000. For moderate disease and moderate risk, a drug is 1 in 1,000; and for severe, this is risky drugs, is 1 in 100. Those are the numbers to put in the balance. And we know the numbers from the drugs, and we must tailor our decision based on that.
MSDF
Are the risks you're looking at purely progressive multifocal leukoencephalopathy, PML, or are there other risks you're considering in those numbers?
Dr. Fernandez
No, PML is just something that appear, but there are many other things to be taken into account. I mean all severe adverse events should be taken into account, and these are the numbers I have mentioned. MS is a very severe disease; it's a risky disease. So we can theorize independent of the severity of the disease and we must look for everything. I mean hematological alteration, hepatic alterations, opportunistic infections, and everything that can be produced by these drugs over these therapies.
MSDF
Is it only the drug or do you also take into consideration patient characteristics besides their MS; age, comorbidities, gender, lots of things?
Dr. Fernandez
Everything has to be put in the box; I mean all the things have to be consider. And it's not the same to use a drug in a patient which is also a hypothyroid, is diabetic or whatever. So comorbidity, age, sex, and everything has to be taken into account, particularly sex because many drugs can affect pregnancy issues. For instance, so we must take it all together and try to get the right decision.
MSDF
Is it a collaborative effort taking into account what the patient preference is either for disease risk, therapeutic risk, or other factors?
Dr. Fernandez
Yeah, I think there is to try to find out which is the best way. We know we has collaborate on that and there are a lot of people collaborating. For instance, in Spain, we have a network of MS, and we are doing tremendous advance publishing in this direction. And in Europe and in the world, I believe there is always networks trying to answer all of these questions. For instance, the latest one has been published more recently about the use of L-selectin to stratify the risk for PML in natalizumab users. And this has been very important collaborative study that has validated this measurement, L-selectin, as a factor to be taken into account to reduce the risk of natalizumab.
MSDF
Is this something new looking at biomarkers for risk?
Dr. Fernandez
Yeah, it's something new. It's still not implemented in most center. But we have been using that for the last two or three years. I have treated more than 250 and especially with natalizumab without a single PML case. Because we use everything at hand to try to reduce the risk of this severe complication.
MSDF
How long have those patients been on therapy, natalizumab?
Dr. Fernandez
Well, the longest one is 12 years already because this patient participated in clinical trials but they are still there. But all of them more than one year. And the majority of them more even than two years. But as soon as the risk gets over the figure that shouldn’t be got, these patients are withdrawn from the drug. And we have medical simulators now to use on different drugs. Although if you are able to keep the patients on this drug, the patients are perfectly well.
MSDF
Do you think the field is going to move more towards that than just looking at JC virus, which is very prevalent anyway?
Dr. Fernandez
No, I don't think we should necessarily look for JC virus in every patient. We must look for other things like, for instance, the cases of PML that appear with dimethyl fumarate. I mean there are two cases, as far as I know, but we must look for lymphocytes. I mean doctors always took care of toxicity degrees one, two, three, and four, and we know what to do with these toxicity degrees. And this has not been well done probably in the last years for some clinicians, so we are assisting to some complications because we don't follow the rules strictly. We must follow the rules. Lymphopenia shouldn't be maintained for long periods. Because lymphopenia can be associated with infections, can be associated with tumors. So we better control for these factors. So let's look everything.
MSDF
Do databases like MSBase add to the knowledge or information?
Dr. Fernandez
Yes, databases probably are fundamental. I mean there are many databases already around the world, and the possibility to share data and to have immediately data from many, many patients is helping us to tailor decisions.
MSDF
Have we missed anything important, or is there anything interesting to add?
Dr. Fernandez
Yes, I think still there is a tremendous variability between neurologists. And there must be some kind of educational effort in the next future to try to reduce variability. Because by now, there are many drugs; we have confusion. Neurologists treat patients very differently in different countries, even into the same country, into the same hospital. So we must still make a tremendous effort maybe through databases or through evidence-based medicine and try to reduce the variability of what we are doing for our patients.
MSDF
Excellent. I appreciate it. Thank you.
Dr. Fernandez
Okay, thanks to you.
[transition music]
MSDF
Thank you for listening to Episode Ninety-four 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. Msdiscovery.org is part of the nonprofit 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.
[outro music]
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.
For Multiple Sclerosis Discovery, I'm Dan Keller.
[intro music]
Host — Dan Keller
Hello, and welcome to Episode Ninety-three of Multiple Sclerosis Discovery, the podcast of the MS Discovery Forum. I’m Dan Keller.
Today's interview features Dr. Lilyana Amezcua, an assistant professor of neurology at the University of Southern California in Los Angeles. Part of her work focuses on defining racial disparities in MS, particularly among the Hispanic community. When we met, she said the prevalence of MS among Hispanics in Latin America has been increasing over the past 20 years, and their clinical characteristics are different from those of whites. As Hispanic Americans constitute one of the largest minorities in the U.S. population, she looked into their clinical picture, as well.
Interviewee – Lilyana Amezcua
And so we initially did a first observation in 2011 noting when we examined close to 200 MS patients of Hispanic background self-identified that they were at twice the risk of presenting with optic neuritis and spinal cord problems compared to whites. There is some literature indicating throughout Latin America that these observations could be related to an Asian background. And so when we think about a Hispanic, we think about an umbrella that is related to an intermixing of European, African, and Asian derived background or Native American. So that diversity along with the cultural diversity could have some implications in the way that MS behaves and including risk. And that is one of the theories going around that that's why they don't get MS that much because of an Asian background. However, again, like I mentioned, in the last 20 years more cases have been reported.
Interviewer – Dan Keller
Haven't Asians been reported to have this opticospinal sort of MS? So would that feed into this optic neuritis finding with the Hispanics?
Dr. Amezcua
That is correct, and actually a second study of ours that we did several years ago was to actually specifically look for that definition of opticospinal MS. And so what we found within 200 or so patients was that indeed when we applied that definition, very few met that criteria. But irrespective of that, and we made sure that every case was negative for aquaporin 4, which is an antibody that you commonly find in more of the NMO spectrum disorders, that these individuals did not have this aquaporin 4, but yet close to 20% looked like they had spinal cord lesions that could be associated with opticospinal.
So that observation, of course, led us to think, well, okay, we should look further. If we do think that Asian ancestry could be important, would some of those clinical characteristics be associated with that type of global ancestry? And in fact today we have a poster related to taking the population that we just presented and looking at their genetic variants, which are mostly noting that the European genetic variants are also found in the Hispanic, but now going forward and looking at, well, what about global ancestry and their clinical characteristics? And in that poster, that abstract, we find that the higher proportion of Asian background you have, the higher risk of presenting with let's say, an optic neuritis. Now that doesn't necessarily say that this is just specific for optic neuritis, but it could going forward let us know about the mechanism behind optic neuritis, which is also found in MS, also found in NMO, and these optical spinal forms of MS.
MSDF
How did you go about looking at the genetics of the population?
Dr. Amezcua
Going about the genetics actually went back to the fact that when I would say, I'm studying Hispanics, people would ask, what is a Hispanic? And it is true…Hispanic…and so it is defined, you know, when you define it it's well, you can be from Cuba, you can be from Mexico, you can be from the US. But really what links us is…and I say linked us because I'm one of them…is the fact that there is a genetic background that is shared. And there's also cultural aspects that are shared. The cultural aspect is probably going to be important when we start examining the environmental aspects of MS.
MSDF
What did you find?
Dr. Amezcua
We just started basically with vitamin D. We looked at vitamin D levels in Hispanics with MS compared to whites with MS, and we found that significantly lower levels were among the Hispanics. This is not surprising. This is expected, actually, because of the skin coloration and sun exposure probably differences, but it's also widely known that Hispanics would have lower vitamin D levels. Of course, that doesn't answer, well, if they have lower vitamin D levels, if their risk of MS is less, it doesn't give us any explanation. But we know that their vitamin D levels are low.
Other aspects that we have looked at is just examining differences by migration. So we know in MS that migration, usually, depending on when you move from one place to the other and looking at the risk of MS in the underlying country, that will be modified depending on the age of migration. And so of course Hispanics in the US, again, along with their diversity, they're diverse in the fact that there are many that are US born and there are many that are immigrants. So we looked at differences by this, and we found tremendous amount of differences. One was that the US born appears to have an increased risk of developing MS at a younger age. And this again is just validating some of that information that we know about MS in the past, right, coming from a lower prevalent region and being born in a place of higher risk.
But the second was that, which we were surprised, was that the immigrant, despite being here, let's say 25 years, they developed MS after they had emigrated from their country, on average, 15 years later. So that's interesting. That's again calling for us to investigate, what environmental encounters might have they had when coming to this country? And the third was that respective of this, of, you know, disease duration, there was an independent risk factor for the immigrant to develop ambulatory disability at a shorter time. So that's telling us that, again, well, one is differential environmental exposures. But could the immigrant and the US-born also just be two different populations in terms of, again, what does Hispanic mean? That's where we are.
MSDF
In that sense, could you correlate vitamin D levels or anything else with the amount of European background or indigenous Central and South American background they had?
Dr. Amezcua
I think that's an excellent idea. You know, I think that could be done, to look at the US-born versus the immigrant. Now there is a large study conducted by Dr. Langer-Gould that's examining the risk of MS within Hispanics, whites, and African Americans in relationship to vitamin D and their HLA. So that will give us information on vitamin D. But absolutely we know that within Hispanics, we're going to have to separate groups because it's just such a big umbrella.
MSDF
It's also a big umbrella in terms of cultural background. It's not uniform culture whether you're from the Caribbean or Mexico or born in the US.
Dr. Amezcua
Absolutely. So culturally we're going to have to tease that out. And it's simply starts by learning about, well, what are those cultural differences? Which could be from simple perceptions and their access and utilization of care, which needs to be first addressed, or to go forward and then say, well, let's see if there's biological differences. First, I think, you know, between the US-born and the immigrant, the differences could be explained also by sociocultural factors. And those need to be teased out. And then from there look to see, well, is this really a health disparity? Or is it an inherent biological difference of the disease, which we also expect to find.
MSDF
Do you think that the results you find in this population is going to be more generalizable or relatable and give you some clues into what's going on with anyone who is getting MS or not?
Dr. Amezcua
Absolutely. That is the goal. While that diversity is complex, it's also a positive aspect because it will allow you to tease out a lot of those factors. And so within the admixture, of the genetic admixture, one can say, well, you have less European background. But what about that Asian component that is not found in your general European? It doesn't mean that it's not going to be found. Instead of looking for, I guess, a needle in a haystack, you will just be looking it in a block and maybe find something new or lead us to understanding of mechanisms, again, from the optic neuritis and the global ancestry. We are hoping that this is beyond just understanding one population, but understanding MS, which is the target population.
MSDF
Have we missed anything important?
Dr. Amezcua
There is definitely a lot to do, and I think it's an effort that cannot be done alone. And so combining it with different centers that have the same interests and population is what the goal is, is to create a network of centers that are interested in defining this population, to move faster.
MSDF
Great. Thank you.
Dr. Amezcua
Great. Thank you.
[transition music]
MSDF
Thank you for listening to Episode Ninety-three 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. Msdiscovery.org is part of the nonprofit 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.
[outro music]
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.
For Multiple Sclerosis Discovery, I'm Dan Keller.
[intro music]
Host – Dan Keller
Hello, and welcome to Episode Ninety-two of Multiple Sclerosis Discovery, the podcast of the MS Discovery Forum. I’m Dan Keller.
Today's interview features a conversation with Dr. Shiv Saidha, an associate professor of neurology in the Division of Neuroimmunology and Neuro-infectious Diseases at Johns Hopkins University in Baltimore, Maryland. His work has focused on the retina in MS, using the technique of optical coherence tomography, or OCT, to follow the disease, assess and monitor therapeutic strategies, and to better understand the pathobiology of MS. I asked him why the retina is of interest in MS and about the utility of OCT.
Interviewee – Shiv Saidha
OCT is the optical analogue of ultrasound B mode imaging. And it's a noninvasive technique that has a lot of utility in quantifying the ultrastructure of various tissues, including the retina. We have a lot of interest in being able to quantify retinal structures specifically in multiple sclerosis because optic nerve pathology, which basically refers to affliction of the optic nerve as part of the MS disease process, is virtually ubiquitous. At the time of postmortem examination of MS patients, 94 to 99% of MS patients are found to have demyelinating plaques within their optic nerves.
So the premise is that demyelination within the optic nerve results in retrograde degeneration of the constituent fibers or axons within the optic nerve. And since those axons or fibers are derived from the retinal nerve fiber layer, which is the innermost layer of the retina, this layer is felt to thin out as part of the MS disease process. Additionally, the neurons – referred to as ganglion cell neurons located in the ganglion cell layer immediately below the retinal nerve fiber layer from which retinal nerve fiber layer axons are derived – are also thought to drop out as part of the MS disease process.
We traditionally conceptualize optic nerve pathology in MS as being an acute phenomenon, namely acute optic neuritis, which does occur in up to, you know, 20 to 70% of MS patients; and in 20 to 25% of cases of MS is the initial hallmark clinical manifestation of the disease process. But beyond acute optic neuritis, there is subclinical optic nerve pathology, which we refer to as subclinical optic neuropathy ongoing within the optic nerves of MS patients.
And so, if we had a technique or an ability to accurately quantify the effects of optic nerve pathology or optic neuropathy – in other words, if we had a way to quantify retinal nerve fiber layer thickness and thickness of ganglion cell…the layer within which ganglion cell neurons are located in the retina – that would provide a substrate or insight into the state or integrity of the optic nerve. And so, optical coherence tomography is a technique which allows us to do this. It allows us to measure thickness of the retinal nerve fiber layer not just around the optic disk which we refer to as the peripapillary retinal nerve fiber layer but also in the macular region.
And with the advent of novel segmentation techniques in OCT – many of which are now commercially available – we now are also afforded the capability of quantifying thickness of other discrete retinal layers such as the combined thickness of the ganglion cell layer and inner plexiform layer, which many of us refer to as GCIP or some also refer to it as GCIPL. Conventionally, peripapillary retinal nerve fiber layer thickness – at least in cross-sectional studies – was found to be associated with high and low contrast visual function, as might be expected since the retina subserves vision as a function.
But interestingly, early studies even found that thickness of the peripapillary retinal nerve fiber layer was associated with disability scores as determined by Expanded Disability Status Scale scores or EDSS scores in MS patients, as well as whole brain volume in MS patients, implying that these metrics derived from OCT somehow provide a window or insight into the global MS disease process. With time, we started to realize that the GCIP thickness might actually be an even more powerful measure of the state of integrity of the optic nerve.
GCIP thickness seems to be more reproducible than that of the retinal nerve fiber layer. It has a intraclass correlation coefficient of about 0.99 with a very tight confidence interval. It has superior structure function correlations with EDSS scores, brain volumes, as well as high and low contrast visual function, as compared to retinal nerve fiber layer thickness. This is really a very interesting and important point about, you know, the potential utility of OCT. Because with this thickness of the GCIP, what we were really getting is a very good estimate of neuronal integrity.
And, one of the factors that has been limited in terms of MRI – or magnetic resonance imaging – is the ability to really accurately and reproducibly quantify collections of axons and neurons. Now in terms of MRI, we often think that the white matter is a very good reflection of axonal integrity, and that gray matter is a good reflection of neuronal integrity. This is not necessarily the case, however. In terms of the white matter, quite a lot of inflammation obviously occurs within the white matter in MS brains. And when that inflammation occurs, white matter volume increases. And then, as that inflammation subsides, the white matter volume drops.
And then, as the next wave of inflammation comes in, again, there's swelling and the white matter volume goes up. And as it resolves, the white matter volume comes down. And so there's this waxing and waning in terms of white matter volume which limits the utility of white matter volume. And in fact, it's for that particular reason that many researchers have found that when you track MS patients over time that the bulk of change is actually seen within the gray matter.
In terms of the gray matter, there is a lot of axons present within the gray matter. And so, gray matter volume is not just a pure measure of neuronal integrity. And the other thing is that the axons within the gray matter are predominantly myelinated similar to within the white matter. And so these brain substructure volumetrics are confounded by myelin too. The retina is an unmyelinated central nervous system structure. And so the measurements that we derive with OCT are not confounded by myelin. And secondly, GCIP thickness does not seem to increase during inflammation of the optic nerve.
There's been a number of studies showing that during acute optic neuritis peripapillary retinal nerve fiber layer thickness increases. There's a number of reasons for that: there's inflammation within the optic nerve, and so there's edema. And so we think that some of that edema may track down to the retinal nerve fiber layer. And there may also be some impaired axonal transport resulting in congested axons within the retinal nerve fiber layer. In addition to that, the retinal nerve fiber layer also contains the bulk of glial cells. And by that, I was mainly referring to astroglia. Now microglia are thought to be present throughout the retina, but there's really no astroglial confound of GCIP thickness as well.
During acute inflammation in the optic nerve, GCIP thickness was not found to increase. And so if you take a patient, as an example, with an acute optic neuritis now, and then you repeat the OCT scan six months later, the GCIP thickness at six months subtracted from that at baseline is felt to be a fairly accurate reflection of net neurodegeneration in terms of net loss of ganglion cell neurons. That absence of edematous or inflammatory or swelling related confound of GCIP thickness yields yet another advantage for this particular measure.
Interviewer – Dan Keller
How does the time course of changes in the GCIP correlate with brain MRI? Can it be predictive or are they in lockstep or how do they relate?
Dr. Saidha
Yeah, so that's a great question. I think one of the things with OCT research has been that the bulk of research to date has been cross-sectional. And so it has really been one of those key things on our mind is does the way that the GCIP atrophies or thins really mirror what's happening in the brain? In other words, are they locked in together? Are the rates of GCIP atrophy and brain atrophy actually associated with one another, or are they a little disconnected?
So in a recent study, which we published in Annals in Neurology, we tracked a little over 100 MS patients for roughly a four-year period, and we did annual MRI scans with a 3-Tesla scanner, and we did six monthly OCT scans. And very importantly and interestingly, we found that the rate of GCIP atrophy was highly correlated with the rate of brain atrophy and a particular rate of gray matter atrophy. Of course, that's a little bit to be expected partly on the basis of what I said earlier that white matter atrophy in itself is not as well detected as gray matter atrophy.
And then when you look by subtypes of MS – meaning, you know, relapsing MS versus progressive MS – we found that the rate of atrophy was even better or more highly correlated in terms of its association with brain atrophy rate. In fact, it appeared that the rate of retinal atrophy could predict 80% of variance in rate of brain atrophy, which is fascinating because it really does imply that what we're seeing within the retina of MS patients is a reflection of global central nervous system pathology.
And the pathobiological changes that we can detect and monitor with OCT appear to very nicely reflect what's happening within the brain. And that this cheap, noninvasive, easily tolerated, easily repeatable technique that's painless can provide so much insight into this disease process is really quite fascinating and really phenomenal when you consider the increasing and growing need for an ability to measure and monitor neurodegeneration in this disease process. We traditionally conceptualize MS as being an inflammatory demyelinating disorder of the central nervous system, and absolutely there's inflammation that occurs as part of the disease process. And when acute inflammation occurs, there's some immediate damage to axons on the form of axonal transection. And then when axons do not have enough myelin around them or are devoid of myelin over sustained periods of time, that normal protective environment for axons is not present, and so we feel that those axons slowly neurodegenerate.
The advent of putatively neuroprotective and putatively remyelinating therapies now more than ever increases our need for an ability to be able to track neurodegeneration. And in fact, it is neurodegeneration that is the principal substrate of disability in MS. And while the inflammation may be at the root cause of this neurodegeneration, the disability that patients have is better associated with the amount of neurodegeneration that's present. So, it's possible – and we postulate – that OCT could be a very useful outcome measure in terms of assessing therapies which are putatively neuroprotective and/or even neurorestorative or remyelinating.
MSDF
Do you think that there is a common process going on more centrally and in the retina causing the changes in both? Or is it possible that there is more central degeneration, which then is transmitted peripherally causing problems in the retina?
Dr. Saidha
So that's a great question. We think that the bulk of the retinal changes that we're observing are related to pathology within the optic nerve. And because optic nerve pathology is basically ubiquitous as part of the disease process, we think that the changes that we're seeing within the retina are really just a reflection of what's happening throughout the central nervous system.
Now, you do raise a very important point though. Although we think that the bulk of the change that we're seeing within the retina is related to pathology within the optic nerves, that does not exclude the possibility that some of the changes that we're seeing – in terms of thinning of the retinal nerve fiber layer and GCIP, in particular – are actually related to transsynaptic degeneration. Meaning that if you have a distant lesion or distant pathology that as an axon dies that the next neuron and axon, as part of a sequential chain, is not affected. And that's something that we're actively studying at the moment to try to better understand the effects of transsynaptic degeneration on retinal measures. There is some data to suggest that there is transsynaptic effects on retinal measures, but my own view is that longitudinal studies to definitively establish this are currently lacking.
MSDF
Do you have to watch out for a history of optic neuritis when you look at the OCTs? Does that affect what you're finding?
Dr. Saidha
I think it does. So, if we are kind of going to say that what we're seeing in the retina is a general reflection of what's happening in the brain, we have to at least consider the possibility that a severe inflammatory event with disproportionate local retinal tissue injury might have an affect on the global relationships between OCT derived measures and brain measures. So, when we look at the relationships between rates of GCIP atrophy and rates of brain atrophy, we find that in eyes with a history of optic neuritis that that relationship is not as strong. And we think that that may be the case because immediately following optic neuritis there's an excessive amount of local tissue injury. And that local tissue injury that results in excessive loss of retinal nerve fiber layer and GCIP tissue somehow masks the global information that we're deriving from OCT.
But then what's interesting is that although a history of optic neuritis seems to be relevant at least in the relapsing-remitting subtype it seems to be less relevant in secondary progressive MS. Part of our hypothesis for this – although it needs to be better elucidated and studied – is that brain atrophy continues on following the optic neuritis, and let's just say it carries on, as an example, at the same rate that it did beforehand. Well eventually, the rate of retinal atrophy, although there was initial disproportionate surge in neurodegeneration within the retina, there will be some ongoing neurodegeneration occurring too. And eventually the two rates will become realigned again in the future.
Kind of to get at that point we also looked at rather than just history of optic neuritis we looked at whether baseline GCIP thickness might have an impact on rate of GCIP atrophy to kind of expand a little bit upon that hypothesis. And indeed, what we found was that rate of GCIP thickness at baseline is highly associated with rate of GCIP atrophy. In kind of simplistic terms the way I conceptualize this is that the more retinal tissue that's available the faster the potential rate of retinal atrophy is. And if there's less retinal tissue available, then there's maybe less potential for that rate to be as fast. If the rate was to remain steady the entire time from the day that the disease first begins – and I think this also applies to the brain too – it wouldn't be very long before there's no tissue left.
MSDF
You had alluded to looking at new potential therapies using OCT as an outcome. Does that also mean that it may have utility in looking at current disease-modifying therapies and being able to compare them?
Dr. Saidha
So that's an excellent question. In fact, that's actually currently no data available that I'm aware of that has assessed the effect of currently available disease-modifying therapies on rates of GCIP or retinal nerve fiber layer thickness atrophy. And I think that's something that a lot of academics and people who do research utilizing the visual system and a particular OCT would be interested in seeing. We have such data – and such data is routinely collected in terms of effects of disease-modifying therapies – on brain volume, and this is something that's now fairly standard to be collected as part of clinical trials. It may be useful to know whether currently available disease-modifying therapies have differential effects on rates of retinal atrophy. Which would imply that maybe in addition to having a role as an outcome measure in trials of putative neuroprotectants, as well as neurorestorative agents, that maybe OCT might actually also have a role in studies of potentially anti-inflammatory treatments or treatments which modulate or suppress the immune system, as do most currently available licensed disease-modifying therapies.
MSDF
Very good. I appreciate it.
Dr. Saidha
Thank you very much.
[transition music]
MSDF
Thank you for listening to Episode Ninety-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. Msdiscovery.org is part of the nonprofit 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.
[outro music]
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. For Multiple Sclerosis Discovery, I'm Dan Keller.