Hello, and welcome to Episode Forty-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. Lawrence Steinman, who discusses a surprising result involving amyloid, a molecule typically associated with destruction in Alzheimer’s disease, in an animal model of MS.
Our Drug-Development Pipeline includes continually updated information on 44 investigational agents for MS. During the past week we added 1 new trial and 16 other pieces of information. The drugs with important additions are dimethyl fumarate, daclizumab, glatiramer acetate, and natalizumab. To find information on all 44 compounds, visit msdiscovery.org and click first on Research Resources and then on Drug-Development Pipeline.
According to our curated list of the latest scientific articles related to MS, 50 such articles were published last week. To see last week’s list, go to msdiscovery.org and click on Papers. We selected one of those papers as an Editors’ Pick. It’s a meta-analysis of epidemiological studies of neuromyelitis optica, also called NMO or Devic’s disease. The conclusion of the meta-analysis is that there’s a high level of heterogeneity among the 9 studies that met the inclusion criteria. The prevalence of NMO in the studies ranged from 0.51 per hundred thousand in Cuba to 4.4 per hundred thousand in southern Denmark.
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Now to the interview. I spoke with Dr. Lawrence Steinman, professor of neurology and neurological sciences, pediatrics, and genetics at Stanford University, who has a new twist on amyloid, this time in MS.
Interviewer – Dan Keller
Dr. Steinman, you have proposed that amyloid can be a protective molecule as well as what’s commonly viewed as a destructive molecule. How did you come upon this?
Interviewee – Lawrence Steinman
We came about it serendipitously or by accident. I had a graduate student and I thought I would give that student some low-hanging fruit, and the low-hanging fruit was to take the conventional animal model that we use for multiple sclerosis called experimental autoimmune encephalomyelitis – EAE. And when she put in these long peptides from an infamous protein named amyloid beta – A-beta – she put it into the animals with EAE at the time they were paralyzed, and I thought well, these are molecules that cause even more inflammation in the central nervous system, so they should make the disease worse, or perhaps they’ll have no effect and then we’ll have to think of another project for her PhD. So the student, Jacqueline Grant, came back and said, “Well, I gave the A-beta peptides and the animals are all better, they’re walking around.” And I first reacted, no, you must have confused the cages, let’s do it again. And when we did it again there was the same result, so then we were off to the races.
There was a second reason besides the low-hanging fruit description. May Han, my colleague, and I had reported the proteomics of MS lesions; so we took well-defined MS lesions, May cut frozen sections and then removed the lesion area with a laser tool, and then we trypsinized, fragmented the proteins, and used a modern technique, mass spectroscopy, to get the proteome, a list of all the proteins in the lesions. So amyloid proteins such as amyloid precursor protein and cal protein are found in the lesions themselves, so I thought that that was a second opportunity, a second foundation for doing these experiments in EAE; let’s see what happens when we augment, if you will, a naturally occurring protein found in the lesion to see perhaps what it’s doing. But, again, my bias, based on the dominant theory in Alzheimer’s disease is that amyloid was going to cause harm in MS as well as Alzheimer’s.
In these experiments, the amyloid was injected IV so it seems to circulate, but does it get to the brain in these mouse EAE models?
Actually, it does not get to the brain. We’ve actually put it into the brain directly to see if it would spread throughout the brain, and in our hands the molecules we’re working with do not spread. Most of these experiments showing a prion-like spread of amyloid is done in animals that are overexpressing the amyloid proteins in the brain so that they’re sort of tilting the balance to enhance spread if it’s going to occur, but we don’t get these amyloid molecules into the brain when we inject them intravenously, nor do we spread them around when we injected them directly into the brain.
So if you’re injecting them peripherally, do you think that there is some direct effect, or do you think they’re acting through lymphocytes or other circulating cells?
Well, we now know that there are at least two mechanisms. One is that when we are injecting them peripherally, these amyloid-like molecules, they go to sites of inflammation and this could include sites of inflammation within the brain. But remember, they’re on the vascular side of the lesion. And they act in a way like molecular sponges. The amyloid molecule is very sticky; in fact, when you try to work with some of the amyloid molecules, they’re like bricks, they stick to the walls of test tubes, and more importantly, they stick to each other and form these long, brick-like fibrils.
So what they’re doing when we put them into the circulation is they’re sopping up many of the inflammatory mediators that appear in the circulation during inflammatory diseases, including inflammatory diseases of the brain. These inflammatory mediators include the complement proteins and some of the famous apolipoproteins that we’ve heard about in reference to Alzheimer’s, we’ve heard the most about apolipoprotein E. So these amyloid molecules, when they’re in the circulation, actually stick and take away, precipitate away these inflammatory mediators. So I call it a molecular sponge.
There’s another set of mechanisms that we’re learning about that we’re able to use these amyloid proteins to do a couple of things to lymphocytes. One, it sets up a type 1 interferon response in lymphocytes. So the amyloid fibrils are a known trigger for the production of type 1 interferon, and type 1 interferon is actually beneficial for neuroinflammation; we have approved drugs. It’s doing another thing that we’re on the verge of publishing, but I’ll sort of give the headline without too many details; it’s setting up a type of lymphocyte that has a more regulatory function. So these are all rather unexpected roles for amyloid proteins.
And you have done adoptive transfer of some of these lymphocytes and find similar effects?
Yes. And the adoptive transfer experiments are very interesting. When we set up the system to produce a lot of type 1 interferon after we give an amyloid fibril, if the type of disease is what’s called the Th17 disease, the increased beta interferon actually worsens that, and if we create a disease that is called T-helper 1 – Th1 – then the type 1 interferon is beneficial. So we’ve engineered some amyloid structures so that they trigger less type 1 interferon, and when they trigger less type 1 interferon, then they work in both the Th1 and Th17 models. We published on that in the Journal of Experimental Medicine. But, again, even here with the type 1 interferon, the effect is nuanced and we can engineer these amyloid structures to be really beneficial and to take away the harm.
I wanted to say one thing, that clinicians and working scientists generally understand amyloid very well. Amyloid-beta that’s well known. Other amyloid proteins that people are, of course, familiar with are tau, prion protein, alpha-synuclein. But an amyloid structure is a general description of a protein that forms beta sheet, so the beta strand structure allows through hydrogen bonds the formation of what you should think of as a venetian blind, these monotonously parallel sheets that actually intercalate dyes, like Congo red or thioflavin T, so that when you shine polarized light on them they refract it in a polarized way. So we can make these structures, if you will, they’re organized nano particulars, to be more or less water-soluble, to be greater or lesser inducers of type 1 interferon. So there’s a whole armamentarium of very interesting amyloid structures that we can engineer to provide benefit in different situations.
Now what does this all mean for the Alzheimer’s hypothesis? And we’re doing an audio interview, so I’m sort of smiling wryly. I don’t want to get into that because we haven’t done the experiment in the amyloid-beta overproducing transgenic mice that have served as the model system to test whether various amyloid-lowering procedures will provide benefit, we just haven’t done that. And we’ve tried our particular approach in a number of other conditions ranging from stroke to EAE, as I said, to experimental heart attacks. And in the systems that we’ve studied, we see benefit.
But as a further proof of concept of what you have found in the protective effect of amyloid, you’ve looked at amyloid precursor protein knockout mice. Is that right?
Yes. Well, that’s a whole interesting story, and thanks for reminding me. So in a series of experiments that we have done and others have done, we first noticed that amyloid precursor protein knockout mice, they had worse EAE. Another person in Australia, Colin Masters, who’s actually one of the leaders in the field of Alzheimer’s research, looked at experimental head trauma, and in the amyloid precursor protein knockout mouse, they had a worse condition after head trauma that was alleviated by giving amyloid precursor protein in its soluble form. And then other people have shown that experimental encephalomyelitis is worse in prion knockout animals and in tau knockout animals.
We had been working with a protein called alpha-B crystallin, which is also an amyloid-forming protein, and we noticed that EAE was worse in the absence of alpha-B crystallin. So there’s a long series of experiments that loss of function, loss of the parent protein of these amyloid-producing molecules, leads to worsened inflammation, whether it’s EAE, head trauma, or somebody else did it in experimental heart attack. And we also did it in experimental stroke, so under a variety of conditions.
So this makes the argument even stronger, suggesting that amyloid structures when augmented can provide benefit and reduce inflammation, and when absent can actually exacerbate inflammation; so gain of function better, loss of function worse. So you have to look at the amyloid molecule as something that is not always harmful and pathologic. Whether it is the main culprit in Alzheimer’s, whether Alzheimer’s is an example of neuroinflammation, I leave it to people in that field because I really don’t want to take them on headlong at this point in time when we have all these fascinating results elsewhere. But I let the listeners draw their own conclusion based on the published work that I’m talking about, not only from my own lab but from other investigators all over the world.
One might want to think a little bit differently the next time one thinks about the deleterious effects of amyloid in Alzheimer’s, but I’m not going to be the one that takes on that massive scientific opinion, we’ll just have to see how it works out. I hope everyone’s been right over all these years because we certainly need some answers in that field. And if they are right, then we’ll have to integrate the kinds of things that we’re understanding about the role of amyloid proteins in other types of inflammatory conditions with a positive result in Alzheimer’s when it’s taken into the clinic. If it turns out that the experiments do not succeed in Alzheimer’s, then it will be easier to reconcile these different outcomes. But I think we’ll have to be patient; science doesn’t move as fast as some of us would like to have it move.
What was the time course of seeing a result by injecting the amyloid in your EAE models?
It’s very fast. When you inject the amyloid, it’s within 48 hours. If you stop giving the amyloid – we like to give it every day – if you stop giving it for a few days, the inflammation recurs, and that suggests that these amyloid structures are acting like a pharmaceutical. It’s not one of these situations that you sometimes see in science; you give the molecule once or twice and the disease goes away forever. This seems to be suppressing ongoing inflammation while it circulates, and when you take it away the effect is gone and the disease recurs, so that’s very interesting.
The effect seems to be too quick for remyelination to be occurring as the answer, but when you give it chronically do you see remyelination?
So far, we haven’t looked for long enough periods of time or with sensitive enough techniques. Your question triggers an experiment and we should really take a look at that. I would imagine that if you can abrogate inflammation that you’ll allow for remyelination if there’s anything left in the oligodendrocyte precursor to remyelinate itself, or if you need a little augmentation, it would be good to do a stem cell type of therapy under the protection of this kind of antiinflammatory approach.
Are you planning any early human trials?
Ha! I chuckle because this is a tough one to bring into the clinic. I’ve been funded by people who first scolded me for saying don’t take this too fast into the clinic, because I like to translate results. In this one, we’ll have to be more cautious than we might for other types of therapies.
Is there anything important to add?
I thought the questions were very comprehensive. And as you can see from where our matters stand now, there’s a lot of positive leads to pursue. And I think we’ll have to be cautious about translating in the fields of multiple sclerosis or stroke because of the infamy of the molecule I’m working with, but we’ll get there. Thank you.
Thank you for listening to Episode Forty-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.
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