An Interview with Ron Davis, PhD, and David Systrom, MD Transcription

An Interview with Ron Davis, PhD, and David Systrom, MD 

Dr. Meadows: Hi everyone, and welcome to a new series of interviews with OMF’s Directors of our research centers. I am Dr. Danielle Meadows, OMF’s VP of Research Programs and Operations, and for this series, I’m going to be talking to each of our directors in pairs and then wrapping things up with a panel discussion with all of our directors.

So, during these interviews, I’ll really be asking them about their big picture hypotheses of ME/CFS and, trying to draw some connections between their research. So, for today’s pair, I am very pleased to be joined by Dr. Ron Davis, the Director of our Collaborative Center at Stanford University, and Dr.David Systrom, the Director of our Ronald G. Tompkins Harvard ME/CFS Collaboration. So, maybe Ron I’ll start with you. If you could give a brief overview of your hypothesis of ME/CFS.

Dr. Davis: Well, our major hypothesis is that this disease is caused by the activation of what we call the Itaconate Shunt. And it’s a fairly recent discovery and we think it gets somehow locked on and, we don’t know the mechanism of that.

So, that’s where most of our efforts are in. This is a major collaboration with Robert Phair, and Chris Armstrong has been involved in it because he can provide some of the analysis as well. He is a young investigator that’s really, really growing in the last several years working in this field.

I’m really impressed with him. And Robert Phair is unbelievably valuable, even though I think a lot of other scientists don’t recognize the value of it because he’s a modeler, he doesn’t do experiments. He simply takes an idea, and he can model it given the data that’s available. And these models can get very complicated as you might imagine.

And it’s sometimes it’s impossible to keep it in your head, but he’s working on trying to put together all of the pathways in the mitochondria and such, that if you tweak one thing, you know exactly what the cascade of effects are. And that’s absolutely essential. His background is electrical engineering, and that’s what electrical engineers do too.

That’s why there’re these complicated electrical things that we have, like computer chips, which you can’t even keep in your head of why they work. You have to model them. So, the Itaconate Shunt really is siphoning off metabolites from the citric acid cycle, which is your major energy generation pathway that generates ATP and that’s in every cell.

So, what we don’t know is if there’s the Itaconate Shunt on every cell, we don’t think so, because of some global measurements that have been made by Robert and also oxygen consumption. So, it may only be in some cells, but that’s enough, and we don’t know where it’s located. And also, that’s why Michelle James is absolutely critical because she can do probes on whole body scans to tell us where these particular components are in.

Some of that early stuff looks like it’s in muscle, as well as immune cells, but unfortunately, immune cells are basically all we can study. So, the Itaconate Shunt is something that’s natural, it’s when you get an infection, it gets activated, and when it gets activated, you feel tired.

And that’s one reason why to think it may be important, because it is something that happens when you get an infection, and the symptoms of tiredness is something that keeps on going with ME/CFS, so it makes a lot of sense why you feel tired. One of the effects of the Itaconate Shunt is that it’s, the Itaconate itself is an anti-microbial, so it’s able to kill bacteria, but it also can shut down a number of other enzymes, and that’s also what Robert is looking at. And those shutdowns of other enzymes may also contribute to the symptoms.

And we haven’t really pictured, since this is fairly new, we don’t even know necessarily what everything it can possibly do, but that can account for a lot of the symptoms. And so, we’re trying to explore more about this. And one of the problems are the complexity of the whole system. We can handle certain things, we have a certain skillset, but it’s not enough. And so we have been launching a number of collaborations within Stanford, but also with the University of Utah.

And that was initiated by Baldomero Olivera, which his nickname’s Toto, and he’s an advisor to OMF as well. And he wanted to do something for this to help OMF and also help our lab. So he set up this collaboration and picked what I consider people who are very intelligent but not arrogant. And that’s my standard. These people you can easily work with and they just know what they know and they stick to that and provide tremendous benefit. We’ve also gotten the Bateman Horne Center involved. They are actually in Utah. They’re actually very close to the university. So that’s a medical output as well, which we absolutely need.

So it’s a really good collaboration for working on this. We’re using some of the Utah facilities, like the mass spectrometer facility, and, there’s an expert that runs that facility. He’s an expert in mitochondria. We also have some chemists that are involved, medicinal chemists, and they actually can develop assays for things and even make modifications of chemical of drugs to make specific tests of hypothesis.

They have a number of assays that they have set up for the activation of Itaconate Shunt, which is vital for what we’re doing. And then there’s the Randall Peterson is, he talked at our working group and also at the community day, he set up a zebrafish model. Zebrafish are very important for this because they’re so fast to manipulate.

And you can integrate a gene or modify a gene, and get it incorporated into them much, much faster than you can do in mice. That’s not to rule out mice models, but they’re just slower do and more expensive. So you, when you do a mouse, you can work with several mice. But when you do with zebra fish, you can do thousands and thousands of zebra fish.

He does these on 96 well plates, and you can get a thousand fish in one plate and then you can do hundreds and hundreds of plates. So, it’s a big level. And so, one of the key experiments is that they have been able to control the Itaconate Shunt and can turn it on. And when they turn on the Itaconate Shunt, the zebra fish swim slower when they take one of their drugs that, or that they found inhibit, and this is not necessarily going to be a drug for people, but it is something that biochemically can shut down the Itaconate Shunt when they use a chemical compound to shut it down, the fish swim normal.

The reason for doing these kinds of experiments is we don’t know whether these drugs that we might try, can get into a cell and then if they get into a cell, can it get into the mitochondria. So, this is an assay that the drug can get into the mitochondria because that’s where the activity is. The other aspect of this, and it gets more complicated, is that we have discovered working with a student in Mark Davis’ lab, that there’s a lot of oxidative damage going on in the patients that’s been known before, but not studied.

And so this oxidative damage can easily to be seen, just looking at metabolites. There’s a lot of metabolites that are clearly been oxidized and, there are some key components that we see have been oxidized. For example, the good one I think that’s easily seen is cysteine, which is amino acid. It has a sulfhydryl group, which is a sulfur and a hydrogen. Well, that can be easily oxidized to sulfate. And if it’s oxidized to sulfate, it can no longer be used. But it also causes headaches. So, we’re beginning to piece together looking at things like maybe these oxidized products, can actually cause a lot of the symptoms and in some cases, we can look to see whether we can tampon it down and make things better.

We’ve tried a number of things of that type. I’ve tried a lot with my son with vitamin C, which seems to have helped him. But we can actually do actual studies to look at these compounds with when we have patient care. And that’s the vital component with the Bateman Horne Center. They have patients coming in and they can do clinical trial, low level clinical trials. The problem is the expense of the clinical trial. So, we have to generally have a fairly small level clinical trial to keep the cost down, but I think we can learn a lot from those clinical trials.

Dr. Meadows: Yeah, definitely. It’s great that you’re able to kind of piece these things together and you have some really wonderful collaborations to try to test some of these hypotheses, so that’s great.

Dr. Davis: Yeah. So, one of them is that BH4 is easily oxidized. We’re looking into that and we’re trying to launch a study, looking at BH4 and its level. We’ve spent a lot of time developing a really good chemical assay for that. That’s using an HBLC column, that’s kind of a classic way to do modeling at studies and early on that looks encouraging, and we’ve also have been studying a yogurt that patients have told us about, which they say it sometimes makes them feel much better.

So it was advertised as a BH4 yogurt because the organism is making BH4 and releasing it into the yogurt. Turns out that’s not true. We’ve been doing mass spectrometry of yogurt and some of the students have been involved at going to the store and getting different yogurts and then doing mass back on them and analyzing what’s in them. We’re getting that pretty well figured out that there are certain organisms can make things. BH4 looks very much like folate, chemically, and so several of the first steps in the pathway of BH4 and folate are the same. Some people have mutations in those early pathways, which means they can’t make some of the folate compounds and they can’t make BH4 products. And it’s possible that if they have that mutation, then the yogurt helps them, but not all yogurts.

Dr. Meadows: Very interesting. Thanks for that overview, Ron. I want to turn it to David briefly to talk about your kind of overview of the disease, what your hypothesis is of what’s going on here.

Dr. Systrom: Sure. Thanks Danielle, and thank you Ron. I’m happy to have had you go first, and I’ll try to link some of our thoughts with, your own as well, because I think there’s a huge amount of overlap, not coincidentally. So, I think many of us in the field, me included, believe that ME/CFS is often, not always, but often post-infectious. And then for not totally clear reasons, there is autoimmunity, which may run amuck on overdrive with associated inflammation. And then downstream of those pathways, we think, there are some issues with oxygen supply to the body.

And we focused on, in particular, supply of oxygen to the exercising skeletal muscle. And, issues potentially with the use of that oxygen by the mitochondrion. So, our large focus has been on oxygen supply during exercise to the muscle using invasive cardiopulmonary exercise testing, and then ultimately, it’s uptake in utilization by the mitochondria.

And I think, in those latter two categories, there’s a substantial overlap with what Dr. Davis was just talking about, that at the end of the day, we may be talking about inadequate or aberrant metabolism in the cell, including multiple tissues, but the skeletal muscle as well. We’ve made some discoveries, we believe in the field, that suggest oxygen supply can be compromised by inappropriately dilated blood vessels on the venous side and potentially on the arterial side as well. So, on the venous side, we call this preload insufficiency. We have evidence with catheters during upright exercise where gravity is the enemy that the veins are inappropriately dilated.

They’re not being squeezed down properly during exercise, especially intense exercise to prime the pump, as it were, to get blood back out of the legs and the abdomen up to the heart so it can do its job. So that’s one component of oxygen delivery, moving blood in that fashion. Normally or in the case of ME, we believe in a overwhelming majority of patients, 90+% that we’ve studied have this element of preload insufficiency. And then on the arterial side, it’s maybe a little more complicated. We have some evidence of a systemic vascular abnormality where the increased cardiac output during exercise is not appropriately diverted to the exercising skeletal muscle, and even more particularly to the muscle fibers, the so-called slow twitch muscle fibers, that are replete with mitochondria. So, if blood is not regulated, the blood flow is not regulated properly during exercise. There’s what we call a defacto left to right shunt.

The blood may be diverted to other organs that do not need the increased cardiac output and oxygen delivery during exercise, things like the liver, the kidney, the gut and maybe even microvascular within muscle may not be diverting oxygen properly to the mitochondria. So, these are all O2 oxygen supply issues, priming the pump on the venous side and getting it properly to the mitochondrion on the arterial side, but then, as Dr. Davis mentioned, there is keen and growing interest in a lot of angles on this, that the mitochondrion itself may be abnormal in this disease, in ME. And there is a number of different angles in that, Dr. Davis mentioned at least one of them or a couple of them. We’re attacking these things these notions with a series of muscle biopsies, needle muscle biopsies, at baseline and then after exhaustive exercise to examine post-exertional malaise, in a prospective study funded by OMF, and thank you very much, we are freezing those muscle biopsy samples, sending them to Baylor, where they’re analyzed for electron transport chain function. It’s the mitochondrial power plant as it were.

What we have found in a preliminary fashion with the help of Bob Naviaux is interesting. There may be a double hit in at least some patients with ME/CFS. One is a reduction in mitochondrial number in the muscle, and the second may be additionally dysfunction of the mitochondrial electron transport chain.

So, defacto function problem that lead both of those things, we think may lead to inadequate oxygen uptake and utilization and energy production during exercise. The one other clinical trial angle that we’re using that supports hypothesis in the end, but obviously we hope will help treat patients is the so-called LIFT trial, LIFT, also funded by OMF. We’re using two drugs we think have been useful in the clinic in ME and Long COVID, and those are pyridostigmine or Mestinon, which is a POTS drug, which is thought to help regulate blood vessel tone. So that addresses some of the oxygen delivery issue and helps with what’s called dysautonomia.

Then low dose naltrexone is the other drug we’re using alone or in combination with the pyridostigmine, which is thought to be anti-inflammatory. So, we’re using those things with a variety of biomarkers, with the help of multiple collaborators within OMF, including Dr. Davis, where we get bloodborne biomarkers, proteomics, metabolomics, transcriptomics, lipidomics, peripheral blood mononuclear cells going to Cornell.

And what we’re hoping to understand with the clinical trial with using these two drugs is A) do they work, but B) if they do work, does it give us better insight into the pathogenesis of the disease? And then maybe moving forward, we can enrich future clinical studies with a focus on subtypes of ME/CFS and really direct our therapy.

So, hypothesis is largely post-infection, autoimmunity, inflammation. Dysautonomia, that’s a nerve problem and therefore O2 supply. And then finally, a subset of patients with problems with oxygen utilization, maybe the mitochondria is the problem there.

Dr. Meadows: Awesome. Thanks David. And, you did a good job already kicking us off with some connections between your research, so thanks for that.

I know, so you talked a little bit about, you know, some of the mitochondria issues that you’re seeing and connecting that to maybe the Itaconate Shunt and the mitochondria issues that Ron has been looking at. So I want to actually talk a little bit about the O2 supply that you were mentioning and maybe draw some connections to some of Ron’s research there.

Where Ron, I think your group recently came out with a publication that’s showing that the red blood cells have impaired capillary velocity under reduced oxygen tension. So, I wonder if there’s connections between the O2 supply that David, your work is showing, and then the reaction of the RBCs to that reduced oxygen level that Ron is seeing. So maybe I’ll open the floor to comment on that.

Dr. Davis: Well, you have to get red cells through the capillaries to be able to deliver some oxygen to different locations. So if that’s slower, it could impact some, but I think overall the oxygen consumption and the person is pretty much the same.

That’s been a big mystery when you measured at a global level. But, that isn’t the whole picture. It could actually be that the oxygen delivery in certain tissues is a critical component, and we don’t know that yet. The other thing that, in terms of mitochondrial number, we looked at that years ago actually in terms of blood cells. And we did that by measuring the quantity of mitochondrial DNA. And that was the same between patients and healthy controls. And some of those were severe patients, but that doesn’t necessarily mean that other tissues are different and especially muscle. And, finding what it is in muscle is absolutely pretty critical component because that’s something that everybody would experience in terms of fatigue.

Dr. Meadows: Well I think it’s interesting you’re talking too about, you know, the differences that you saw in the red blood cell mitochondria count, and then what David has seen in the muscle mitochondria number, where, you know, kind of goes back to what you were saying with the Itaconate Shunt potentially, you know, not being activated in all cells.

So there’s that kind of similar vein that we’re talking about here, where it’s potentially, you know, we need to target more specific tissues or specific cells in order to address some of these issues. David, anything you wanna add to this?

Dr. Systrom: Yeah, I think, so the red cells don’t have any mitochondria. They’re all glycolysis, but it’s the peripheral blood mononuclear cells.

Dr. Meadows: Yes. Sorry, I misspoke.

Dr. Systrom: Yeah, I think, absolutely there can be compartmentation of energy metabolism in different types of cells and God knows, we wish we could have a blood test that reflects all of the tissues. Unfortunately, there can be a disconnect there. And I think, what Dr. Davis said is absolutely true.

Yeah, Bob Naviaux has been impressed that when we compare our most recent data with a needle muscle biopsies, frozen sent to Baylor, that the mitochondrial DNA count is actually down in the majority of ME/CFS patients. That correlates very well with something called citrate synthase activity, another marker of mitochondrial number in ME, but not his prior studies of genetic forms of mitochondrial myopathies, where the numbers actually up in a teleologic sense that’s maybe compensatory for the poor function. So, he thinks this is a little bit of a different animal from genetic forms. We all do, it’s acquired. It’s not, we don’t think it’s genetic and yes, compartmentation for sure is one of the issues.

Dr. Meadows: I think with that we will wrap things up today. So, thank you both so much for your time. I really appreciate you getting on a call to chat with me. And we will say thank you for listening. Alright.

Dr. Systrom: Thanks Danielle for everything you’re doing. Yes, Dr. Davis. Cheers. Nice to talk with you again.