Episode 82 – POTS Matters: Choline Transporters with Dr. Schenkel https://tinyurl.com/potscast82

00:00:01 Announcer: Welcome to the Standing Up to POTS podcast, otherwise known as the POTScast. This podcast is dedicated to educating and empowering the community about postural orthostatic tachycardia syndrome, commonly referred to as POTS. This invisible illness impacts millions and we are committed to explaining the basics, raising awareness, exploring the research, and empowering patients to not only survive, but thrive. This is the Standing Up to POTS podcast.

00:29 Jill (Host): Hello, fellow POTS patients and most lovely people who care about POTS patients. I'm Jill Brook, your hyper adrenergic host, and today we have an episode of POTS Matters. My guest today is Dr. Laila Schenkel, who is a molecular geneticist and researcher who has done a very high tech and impressive investigation into the skin cells of one POTS patient. Yes, that's right, she looked at skin cells, I think. I'm going to double check with her 'cause it was a complex thing, but it was so cool! She looked at skin cells and learned so much that when I read this study, I was really blown away. I did not realize the world of information that is apparently revealed in a skin cell. She did some smart and interesting things and I'm excited to have her talk about it. Dr. Laila Schenkel is currently Assistant Professor at Western University and molecular geneticists at London Health Science Center in London, Ontario Canada. She earned her Ph.D. at University of Guelph in 2014 where she studied the mechanisms of choline deficiency. Her current clinical and research interests involve the implementation of novel technologies to clinical molecular diagnostics and the identification of novel disease biomarkers using epigenomic profiling. Dr. Schenkel, thank you so much for joining us today.

01:56 Dr. Schenkel (Guest): Of course, thank you so much for inviting me to be here today, and it's very impressive and rewarding to know how our research can impact patients' lives. So, thank you.

02:08 Jill (Host): Well, I am excited 'cause as far as I can tell you are the only person doing the kind of work that you describe. But maybe for starters, since you're our first guest who's a molecular geneticist, can you just tell us what that is and what kind of work you do?

02:25 Dr. Schenkel (Guest): Sure. So, my current role as a molecular geneticist involves an interpretation and reporting of a variety of clinical genetic tests. So in our laboratory in London, Ontario, we perform genetic testing for a variety of clinical conditions, and this includes, for example, looking for variants in genes that can cause irregular cancer or genes that cause familial epilepsy or other rare genetic conditions. We also test tumor samples looking for genetic alterations that can be used for example as target for the cancer treatment in that patient. And before you ask, unfortunately, POTS hasn't made the list of genes and disorders that we test. Although there is some evidence for gene alterations that could cause POTS, the evidence is limited and there may be other genes and other causes to be discovered yet.

3:30 Jill (Host): Well, so that brings me to my next question, which is: most people have never even heard of POTS, so what made you hear about POTS and get interested in POTS and especially the skin cells of a person with POTS?

03:46 Dr. Schenkel (Guest): Well, when I was doing my Ph.D. back in 2014, we were studying the metabolism of choline, which is a nutrient that has many important roles in our body. The interesting parts came when a patient diagnosed with POTS showed very low levels of choline and betaine in her blood, so we want to investigate the reason for that deficiency in choline, and also what was the consequence of that deficiency in the body metabolism and functioning? But skin cells, right, are fibroblasts. We needed a model that we could use to study the choline inside the body, that we could look under the microscope and see how choline was behaving in the cells. Fibroblasts are a good model to study the metabolism of nutrients in the cell. Fibroblasts are easy to culture in the laboratory and not too painful to take from the patient. We collect them by doing a small biopsy in the skin and then put them into a medium where we can keep the cells growing.

05:00 Jill (Host): OK, so if I'm understanding this correctly, you were already interested in choline because that's a common and important nutrient in the body. You found a POTS patient who had very low levels of choline and you already knew that skin cells or fibroblasts were a good way to study that. So why, in general, are you interested in choline? What is choline and why did you think that that would be relevant to POTS?

05:31 Dr. Schenkel (Guest): So, choline is what we call an essential nutrient. We get that from our diet, and it is found in many foods such as eggs, liver, and kidney meat. And it is called ‘essential’ because it has many important roles in our body, including for example neurotransmission in the brain, lipid metabolism, regulation of cell membranes, and mitochondrial function. Choline also produces betaine, which is involved in methylation reactions in our body. In POTS, the deficiency in choline could explain some of the symptoms, at least for this patient, that show low levels of choline in her blood. Because choline and betaine have so many important roles in keeping the cells healthy and the body functioning a deficiency of this nutrient could result in many diseases. For example, we know already that deficiency in choline can result in problems in the muscles and liver disease. But we were curious to see what was happening in these specific [inaudible].

06:44 Jill (Host): Right, and it wasn't just that she had a very limited diet, right? She was a pretty normal person with a pretty normal diet, so you did not think the choline deficiency was just that she wasn't eating enough?

06:57 Dr. Schenkel (Guest): Yeah, that's what we suspected.

06:59 Jill (Host): OK, so maybe we can get into your study. What were your goals and what were your hypotheses for this study?

07:08 Dr. Schenkel (Guest): Yes, so the goal for this study was to understand how choline deficiency was affecting the function and metabolism of those cells. Our hypothesis was that many functions in the cell would be altered, such as those involving lipids and the cell membrane and also the mitochondrial function.

07:29 Jill (Host): To me as a non-scientist, does that mean that you expected that the cell membrane would not work properly in terms of letting in what it's supposed to let in? And, I guess maybe... maybe... can you explain like I'm five years old? [Laughs]

07:48 Dr. Schenkel (Guest): Sure. Well, as choline is the precursor of one very important lipid in our cell membrane, we expect that if the cell membrane is not function or has a different shape or a different composition, the cell [inaudible] would be a sick cell, would have maybe a different shape, would not be transferring elements outside, inside, very well. The receptors or transporters could be affected. So, all metabolism function of that cell could have some effect or some problem because the cell membrane would be affected.

08:29 Jill (Host): OK, great. And then I think you also mentioned the mitochondria being involved and that is the part of the cell that makes the energy. Is that correct?

08:38 Dr. Schenkel (Guest): That’s correct and we are going to talk more about that as we evolve on the study, but the mitochondria is also affected in a way, because mitochondria, which is an organelle, has also a membrane that needs the same type of lipids that we have on the plasma cell membrane. So that's why the mitochondria could also be affected.

09:06 Jill (Host): Got it. OK, so the word that I'm hearing over and over again is membrane. If your membranes are messed up, then that will have further effects.

09:17 Dr. Schenkel (Guest): Yes.

09:18 Jill (Host): OK, so who are your subjects in this study?

09:22 Dr. Schenkel (Guest): Our experiments on this study were done with fibroblasts, which I skin cells from a single patient with POTS that had also shown deficiency in choline in her blood. And these fibroblasts were compared with controls’ fibroblasts which are cells from individuals that don't have any known disease or deficiency.

09:47 Jill (Host): OK, and now for the part that I think is so impressive - your methodology. You did a bunch of very impressive-sounding high tech things that probably are only understood by biochemists. But are you able to maybe give us a simplified idea of what you did with these skin cells?

10:08 Dr. Schenkel (Guest): Yes. I'm sure that there's a lot of things if you read the paper, but I'm going to try to simplify that as best as I can. So, what we did on those fibroblasts, and comparing with control fibroblasts, is to start we want to look how choline was entering the cell. So choline use a protein transporter to enter the cell membrane and also the same transporter to enter the mitochondria membrane. So, we first tested how this transporter was expressed, both at the protein level and RNA level. So next, after looking at the transporter, we look into the different pathways that the choline participates inside the cell. So for example, as I mentioned before, for the membranes, the choline produced a molecule known as phosphatidylcholine, which is an important component for formation of the cell membranes. We also look into the lipid composition of the membrane and how that was affected in the choline deficient cells. Next, we studied mitochondrial function. As choline also works in maintaining the mitochondria membrane and its function, and as you might know, the mitochondria are important components of the cells, as they are responsible for the production of energy known as ATP which is needed for many many cellular functions, and it's the energy to our body. So, we tested mitochondria energy production and electrical activity on those cells. And finally, one last step was to treat those cells with choline supplementations and see how we could change that status.

12:03 Jill (Host): OK.

12:04 Dr. Schenkel (Guest): So, in summary, that's what we did in our experiments.

12:09 Jill (Host): Yes, and I know that every step took a lot of very thoughtful high tech, amazing work that when I was reading it in your paper. I was just blown away. So before we get into the details of what you found, can I just ask - so if you look under a microscope at the POTS person’s skin cell versus the control person’s skin cell, would they look really similar until you did all your fancy work or... or would they immediately jump out as different to you?

12:45 Dr. Schenkel (Guest): Well, when when I said we looked under the microscope was really a simplification of what we did.

12:51 Jill (Host): [Laughs]

12:52 Dr. Schenkel (Guest): We look more in depth of the thing, so we don't just look at the microscope and the shape of the cell. We are able to see a difference and I don't think you would be able to see any difference just looking at the shape of the cell into the microscope. So, we really need to go inside the cell, inside the membrane, inside the genes, inside the proteins and see if they are being affected. So, we look more into the metabolic pathways, we look more into the expression of genes and expression of proteins when we do those experiments. And for the membrane, we also isolate the membrane and look at the composition of lipids, for mitochondria we look at the activity of that mitochondria, how is that mitochondria producing energy and consuming oxygen and the electrical activity of the mitochondria. So we need to go more in depth of those cells.

13:52 Jill (Host): OK, so it's not like the POTS skin cells were completely freaky. You had to look pretty detailed and in depth before you find the differences.

14:02 Dr. Schenkel (Guest): Yes, they are not completely different from... from a normal cell, of course.

14:07 Jill (Host): That's kind of reassuring. OK, so let's dig into some of those details. What was the first thing that you found different between the POTS skin cell and the control skin cell?

14:19 Dr. Schenkel (Guest): Yes, our main finding was that the choline deficiency on those cells was a result of a defect on the choline transporter, so that transporter that is on the membrane that carries choline from outside to inside. That transporter had the reduction on its expression, both at the protein level and RNA level. And this could be caused by different reasons that we can discuss more. And the other very interesting finding was when we treated those cells with choline, so we put more choline into the media of those cells, the transporter was activated. So we saw an increase in the expression of that transporter, so it was not something that we could not revert. So when we gave more choline the transporter got back to a normal level of expression.

15:15 Jill (Host): OK, so just to make sure I understand, it sounds like the first difference you found was that the choline transporter system was altered and it was not bringing in enough choline into the cell. But then when you put extra choline into the cell medium, it was able to sense it, detect it, it knew to bring it in, is that right?

15:39 Dr. Schenkel (Guest): Yes, that's what happened on those cells.

15:42 Jill (Host): OK, that sounds hopeful. OK, what else?

5:50 Dr. Schenkel (Guest): So we then look at the composition of the cell membranes and that was changed. As I told you choline, is important for the synthesis of [inaudible], choline and other lipids in the membrane. So we found that the composition of the membrane was changed and that can affect the function of either the cell or the mitochondria, because as I told you, the mitochondria also has a membrane and the mitochondria also has the same transporter. So that's why mitochondria is also very important here.

16:20 Jill (Host): So that sounds like a big deal. If your membrane isn't quite right, does that imply that things might get in or out of the cell, or it might get in or out of the mitochondria improperly, 'cause that that sounds like an important thing - you want to keep some stuff out, let some stuff in and it's not necessarily doing that job properly? Is that what you're saying?

16:43 Dr. Schenkel (Guest): Well, the change we see on the cell composition on the membrane composition, it's not like that before you had one thing and now you have a completely different thing. You see like slight change, you see a reduction on certain types of lipids and increase in other types of lipids. Those cells are still functioning. They are still cells that can function. They have their normal activity. They can produce their metabolites so the cells are still functioning, because if they were not all the cells in their body would not be functioning, and that's not compatible. So the cells are functioning, they just have this slight change that are affecting some types of metabolisms and some pathways inside the cells. So doesn't mean that the cells are totally dead pr are not working, they have some change that we can try to revert or improve. And very importantly here is I like to emphasize the mitochondria. So the mitochondria has the same choline transporter, which we saw is downregulated. And the mitochondria membrane is where the magic happens, it’s where we have the production of energy. And when we tested energy production of those mitochondria, we saw that they were affected. They were producing less energy, they were consuming less oxygen. And this made me think that it's a very important finding and it could explain some of the exercise intolerance on those patients, at least on this patient that we saw the choline deficiency because we need energy for the exercise, right? So when we start an exercise, we need that burst of energy. If my mitochondria cannot provide that very fast or effectively, that could bring me to some certain types of exercise intolerance.

18:47 Jill (Host): Yeah, so your POTSs patient indeed had tried to exercise, couldn't do it, felt worse afterwards, had the classic POTS exercise intolerance?

19:01 Dr. Schenkel (Guest): I don't have a lot of clinical information, but from what I have, orthostatic exercise intolerance was one of the things.

19:10 Jill (Host): So that's interesting to me because we always hear about patients being fatigued or having exercise intolerance, but I never thought about it happening at the level of each mitochondria of each cell, and so that's interesting that you are you are saying that is plausible that that's where that comes from?

19:33 Dr. Schenkel (Guest): Well, that's one hypothesis, especially for this specific patient. Doesn't mean that's the only reason for that, could be a small piece of that puzzle that we can revert because we can supplement and maybe it can help, right? It's not the only thing for sure, but it's something that could explain that piece.

19:55 Jill (Host): OK, fascinating. OK, was there any other differences between the POTS cell and the control cell?

20:05 Dr. Schenkel (Guest): These are the main findings to present here, so would be in summary, the transporter that's being downregulated in both the plasma membrane and mitochondria membrane, the composition of the lipids on the membrane are changed slightly, so don't think that's all different. And the mitochondria function was changed. It was less active on those POTS cells.

20:34 Jill (Host): So that's interesting. And is it correct that it all started with the POTS skin cells having altered expression of genetics? Was that a first step or am I misreading that? Is all of this happening because of a genetic thing or or am I imagining that?

20:58 Dr. Schenkel (Guest): Well, we don't have a proof of that. It could be genetics because we know the RNA expression is downregulated, so the RNA is what comes from our DNA. So something from DNA to RNA is impaired, so we have a lower expression of the RNA for that transporter there. It could be genetics, it could be something on the DNA that is making less production of the RNA. It could be something that regulates that transcription from DNA to RNA and doesn't need to be perceived variant on the DNA, but some external factor that regulates the expression of that gene. But we didn't do any experiment that could prove that. We didn't find anything that explains that for now.

21:50 Jill (Host): OK, so if I'm understanding correctly what you found, you found that the POTS skin cells had a different choline transport. It made the cell membranes a little bit different and that made the mitochondrial function different as well. And taken together, what does all of that mean to you? Does this tell you something?

22:21 Dr. Schenkel (Guest): Well, this study brings more questions than answers at some point, right? [Laughter] But what we have here as the big picture for me is that the study shows that the choline deficiency can result in many altered cellular functions. And that this deficiency can result from dysregulated choline transporter, which takes less choline inside the cells and inside the mitochondria. This finding suggests that, at least for this patient, the choline deficiency could benefit from choline supplementation. And I can tell you that this patient has taken choline supplementation since then, so since the 2014, and reports that it improves her quality of life, helps with energy and tachycardia, especially during episodes of orthostatic intolerance after exercise. So this is exactly the report that I have from this patient that we studied the cells.

23:25 Jill (Host): So that's a big deal. So I guess we should just remind everybody listening that the skin cells came from just one POTS patient and we don't know if she is representative of all POTS patients. Is that correct?

23:39 Dr. Schenkel (Guest): That's totally correct, and I have these here to emphasize on my notes that if this choline deficiency is seen other patients or in many patients or in most of the patients, we don't know. We just test this one that it was detected on her blood test. So she had the blood test and saw that. So we... when I studied what was happening, but we don't know if that's happening to a lot of people or not with POTS or without... without POTS, right?

24:12 Jill (Host): Right, and so it's very hopeful, though that she took a choline supplement and felt better. Is there anything special that made you decide to test her for choline deficiency? Did she have symptoms that made you suspect it, or was she just getting a lot of different blood tests done and the choline deficiency popped up as one? Or I guess, is there anything that would make someone suspect that maybe they have a choline deficiency?

24:42 Dr. Schenkel (Guest): I'm not sure what was the reason they got her tested at the beginning, so this was done of course by her clinician that was with her at that time. So we were on the research lab when we received that information and they want to do more investigation, so we went for it. But I don't know what made the clinician think that could be choline, like stats for choline. I guess they would have tested for like 15 different nutrients and vitamins at that point, and they found the choline there just by chance.

25:18 Jill (Host): OK, interesting and I have one more question, because when I read your article, my first reaction was to be blown away that skin cells would have all this information in them, and so I guess my first question, is it common that you can see a systemic problem in somebody's skin cells? And then basically, would you expect that somebody would have the same problem in their heart cells or their brain cells or their kidney cells, if... if you're seeing this in their skin cells?

25:55 Dr. Schenkel (Guest): Yes, it's a very interesting question. So as I mentioned before, skin cells were chosen as it is a good model to study what is happening inside the cells. We could have studied any cell that we know have a choline transporter and use choline for its function. As a matter of fact, choline transporter is expressing pretty much all cells and tissues, so we would likely have the same type of results if we test the other cells. And remember that when we are doing molecular studies like these, we need to remember that all cells share the same genetic material and if a defect is caused for by a variant in a gene, for example, this would be seen in all cells of our body.

26:43 Jill (Host): OK.

26:45 Dr. Schenkel (Guest): So how a systemic disorder can be seen in the skin cells, right? That's your next question there?

26:52 Jill (Host): Yeah.

26:53 Dr. Schenkel (Guest): So when we talk about the systemic disorder, like POTS for example, we are referring to the phenotype. So what we see, what is expressing, right? And these are the symptoms of the patients. But this phenotype, even though it's seeing many different tissues, can have an underlined defect in one gene or multiple genes. Remember that the genes are present inside the nucleus of each cell and it is inside the cells that these genes will produce the proteins. So, in a simple way, the defect starts within the cell and the protein product can affect the cellular functions, which will then affect the whole tissue or could even affect the function of different tissues, resulting in a more systemic phenotype. So to answer the question, even systemic disorders can have alterations in genes or gene expression that can be seen in a single cell, such as a skin cell.

27:59 Jill (Host): That is so interesting! So, you can see a bunch of different diseases? Can you look at somebody skin cell and be able to know whether they have a number of different diseases, like you have ways to tell from a single cell if somebody has, I don't know, cancer or lupus or whatever?

28:22 Dr. Schenkel (Guest): Yeah, so I can give an example. So outside of the POTS, but here on the clinical genetics laboratory, how we do, we can test either blood or fibroblasts. So we would isolate cells from the blood or isolate and then isolate the DNA from the blood, or we can isolate the DNA from skin cells. The DNA is the same in any cell of our body. So you could isolate DNA from any cell of your body. And it's on this DNA that we test for genetic variants. So any disease that's caused by a genetic variant in a gene that we know, and a classic example that we test here is, for example, for hereditary breast and ovarian cancer, which is caused by brca1 or 2 mutations. [Transcriber’s note: BRCA1 and BRCA2 are the genes most commonly affected in hereditary breast and ovarian cancers.] We can test for those isolating the DNA in any cell of our body. So we can use fibroblasts, but most often we use blood because it's easier to collect from the patient, but fibroblasts are usually the second choice.

29:29 Jill (Host): That's so interesting. OK, I had a new question pop into my head that I don't know if you have an answer to this, but knowing what you know about genetics and changes to genetics and epigenetics. Does that change any of your behavior on your health? Like, are you very careful to avoid, I don't know... like cigarette smoke or like things that theoretically we hear about could cause some damage to genetics?

30:05 Dr. Schenkel (Guest): Yes, so I try to be healthy. It doesn't mean that just because I know that's what happens [Laughs] But in the world of epigenetics and genetics and study a lot of disease that we know they can be caused by a gene alteration, but we can have an effect of the environment together. So sometimes you have the gene alteration, but if you take care of your environment such as not doing anything that can increase your risk to develop cancer, your genetic risk will be a little bit modified. So if you take care of the environmental factors, even though you have a genetic risk, your total risk at the end’s lower. So, and this comes the world of epigenetics, which kind of combines both genetic and environment and gives very important regulation of the gene expressions in our body. And it is associated with a lot of disorders. Many that we know and many that are still being studied.

31:11 Jill (Host): I was wondering if you have any more plans to look at the molecular genetics of POTS.

31:17 Dr. Schenkel (Guest): I would be very interested to look into that. It's very intriguing that we have so many patients with that condition and there is not a single genetic cause, or at least a few handful of genes that we know that could be causing that. It's important to remember we have conditions that are... we call monogenic, which are caused by a single gene, and that when you have that you will have the disease. But there are lot of disorders and the majority of them are known as multifactorial or complex and those are caused by combination of multiple genes that could give you a susceptibility plus environmental factors. And then comes that type of disorder that, yes, you should try to modify environment to help with prevention and so on. So we don't know how its POTS mostly caused by if it's would be caused by a single gene, if it would be the effect of multiple genes combined and plus environment, or epigenetics together. It still needs a lot of research I guess to find the answer for that.

32:28 Jill (Host): Yeah! Well, I'm so excited that someone with your skill set is thinking about this. So I know everybody listening right now is going to have a question of does this have any practical significance right now, or is it too early? So probably everyone out there is wondering if they should go out there and try a choline supplement. Do you have any words on that? I don't know offhand about choline supplements and how safe they are or not. Do you have any words for people wondering about that?

33:01 Dr. Schenkel (Guest): Yes. So as a take away, it's important to understand that not all patients will have the same phenotype of choline deficiency, but a simple blood test could check for that if that's something you are interested and could use to know. So, consider talking to your doctor about doing a blood test and then about choline supplementation. I don't think choline supplementation would have any side effects. It's like a nutrient, you can get that from your diet, but if you are too deficient then you need supplementation. It's like taking extra vitamin D, right? But again, that cannot be the case for everyone, and that's not the cure. As I told you, this could help with few things, some phenotypes, as we hypothesize here. And hopefully it could help many people living with POTS and other people that have deficiency in choline and have things that they cannot explain, right?

34:05 Jill (Host): Right! Well, that's really, really exciting and so important. And yeah, I think I'm gonna call my doctor right after this and say, “Just in case, let's test for that.” But Dr. Schenkel, thank you so much for speaking with us today. We really appreciate your time and I hope that your POTS research continues. I think I speak for our whole audience when I say how grateful we are that incredibly talented people like you are applying your unique skills and knowledge to help the POTS world make progress. So huge, huge thanks.

34:42 Dr. Schenkel (Guest): No, I should thank you. Thank you for interviewing, it's really amazing when we can do research that can have an impact like this. Even though it's small, but it's putting together those small impacts on our research that we can make a big difference, right? So, thank you so much and thank you for listening.

35:01 Jill (Host): Oh absolutely! Oh, this has been great! And OK listeners, I hope you enjoyed today's information. That's all for now, but we'll be back next week. In the meantime, thank you for listening. Remember, you're not alone. And please join us again soon.

35:19 Announcer: As a reminder, anything you hear on this podcast is not medical advice. Consult your healthcare team about what's right for you. This show is a production of standing up to pots which is a 501C3 nonprofit organ. You can send us feedback or make a tax-deductible donation at WWW standing up to pots org. You can also engage with us on social media at the handle, standing up to pots if you like what you heard today, please consider subscribing to our podcast and sharing it with your friends and family. You can find us wherever you get your podcasts or at www.thepotscastcom. Thanks for listening. © 2022 Standing Up to POTS. All rights reserved. [Transcriber’s note: If you would like a copy of this transcript or the transcript for any other episode of the POTScast, please send an email to volunteer@standinguptopots.org]