Scientist Stories: Alice Long, Treg Modulation

This is a special episode of the Immunology Podcast, AAI 2022, Treg and Modulation with Dr. Alice Long. Hey everyone, this is Dr. Jason Goldsmith and Dr. Brenda Raud. Welcome back to the Immunology Podcast where we have conversations with immunologists. This week we're bringing you 3 very special episodes of the Immunology Podcast straight from the American Association of Immunologists annual meeting. Immunology 2022. Today is our last episode. We'll be chatting with Dr. Alice Long from Benaroya Research Institute at Virginia Mason to discuss her talk on Treg modulation by IL-2 mutine therapy. But before we get to that, ensure reliable results with your immunology research.

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All right, Brenda, it's the last one. We're almost at the end of AAI here.

Yeah, well, all good things come to an end.

So luckily there's one next year. So that's always important to remember.

Every year. Where is it next year again?

I don't remember where it is next year.

I think it was Washington, wasn't it?

Oh, is it? Is it? Yeah. Is it Washington, D.C.?

Yeah. Why don't we jump to our conversation with our guest today?

All right. Sounds good.

So continuing with our AAI special, today is the last day of AAI and we're really happy to have one more speaker invited to talk to us. This is Dr. Alice Long, who is an associate member at the Benaroya Research Institute at Virginia Mason in Seattle. So right in the neighborhood of Portland. And she's going to be talking to us about her two talks that she gave on Saturday and Sunday and about her research on Treg mutagen therapy and CD8 T-cell exhaustion. Hi, Dr. Long. Thank you so much for joining us.

Yeah, this is great to be here. Thank you so much for inviting me.

Thank you. All right, let's dive in. So Brenda's favorite, one of her favorite T cells or all immune cells is the Treg, which has been a running theme on our show here. So diving in, you do a lot of work in type 1 diabetes, and I'd love if you could give a high-level overview of the kind of critical role of Tregs in type 1 diabetes for our audience who may, you know, about it from other autoimmunity, but you know, just because it's Tregs are important in one type of autoimmunity doesn't mean they're important in another type.

Yeah, no, it's a great question. And type 1 really is the place where people started asking the questions about Tregs, mainly because of the IPEX-FOXB3 mutations, which— where Tregs are either mutated or gone. And these patients, one of the diseases they get are type 1 diabetes.

And so this—

and then it could also be very easily modeled in NOD mice, which are type 1 diabetic mice, essentially. And so really a lot of the field in asking about Tregs and therapies that can augment Tregs, like L-2-mutines, etc., have been done in the context of type 1 diabetes. And that was one of the earlier trials tried.

You're working in the context of diabetes— I assume it's in the context of diabetes— with IL-2 mutants that are, I guess, directed against Tregs? Did I understand correctly?

Yeah. So, I'm doing this work with ITN and Merck. And so, IL-2 is a supportive cytokine for Tregs. But really, in each individual, that threshold of what expands Tregs is a little different. And IL-2, if you give it in a higher dose, can activate cells, which is great for cancer but not too good for autoimmunity. And so, finding that narrow window has been tricky. So, there's been a lot of effort, I would say, in the last 10 to 20 years to improve upon biology, to make kind of super IL-2s. So, whether that is IL-2 mutine where the— affinity and specificity of the binding is mutated, or there are other ways you can change the IL-2 molecule by adding an antibody complex, by pegylating it to make it more stable. So there's things that we call engineering that natural selection has not done to the molecule that will improve upon its augmentation of Tregs.

Can you give us an example of how you can change an IL-2 molecule to make it specifically bind to T-rex or not? Also, I think in the context of cancer, we want exactly the opposite thing, right?

Yeah, there are a lot of people that are trying quite a lot, quite many approaches. And so some of them are to mutate specific amino acids so that the binding to the IL-2 receptor is lower or higher affinity, but depending on your need.

All right. And so where, where is the field for this? So you talked about some of the initial trials for type 1. We're trying to get Tregs to be engaged better. Where are we in, oh my God, I have signs of type 1 diabetes, right? Or maybe I genetically screen people. I don't know where you're thinking on it, but like an early intervention on the Treg side of the fence to stave off the loss of the islet cells permanently. Where are we in— is this in a Phase 1 state, Phase 2? Are we like— are there Phase 3s going on? Is it still mostly preclinical?

It's a mix. So the molecule itself, IL-2, unmutated, is in later trials across autoimmune diseases. And the engineered mutins and kind of all of the different varieties of engineered IL-2 molecules are on very much earlier trials, many of them just in healthy controls.

So do you think then we're looking at like 5 years until we start seeing IL-2 being used in a context like this?

Oh, wow. When you say being used, that's a tricky term. So in trials, for sure. Type 1 diabetes is a hard bar. We're looking at finally, hopefully, fingers crossed, approving our first drug beyond insulin to treat type 1 diabetes. Um, so in comparison to other autoimmune diseases where there are many approved drugs that are used to treat the disease, insulin to date is it for people with type 1 diabetes. So for drug approval, I think we're always— maybe other autoimmune diseases might get there a little faster, but I do think it'll move faster also, particularly with prior experience with IL-2.

Looking on the other side, so looking also in the context of type 1 diabetes and T-cell-related diseases. So you also having us— you had another talk on Saturday in which you talk about T-cell exhaustion. Was that also in the context of autoimmunity?

It is, yeah. So there are many ways you can regulate autoimmunity, which is a good thing. Our body would fall apart if we didn't have many ways to keep things in check. And so, a lot of people know about CD8 T-cell exhaustion in the context of cancer, where really it prevents destruction of the cancer and is worse for the disease. But in autoimmunity, there is a recent trial with anti-CD3 that's been done more than once that showed an expansion of CD8 exhausted cells. So, these are cells that have the transcription factor EOMS, express a lot of inhibitory factors, and produce fewer levels of cytokine. And so, these cells are associated with better outcome in those trials. So, we took a step back and we said, well, wait a second. If we're seeing this signal in a trial, can we actually see it in the natural population if we look at a large enough population and ask just whether higher or lower levels of exhaustion overall could predict your disease status, in essence. And so, in a large cohort, we had 100 healthy controls and 100 RA subjects, rheumatoid arthritis now. When we looked at those, the disease didn't discriminate between exhausted and not. But actually, DR4 did. And this is an HLA Class II molecule that's associated with risk. NRA. And if you have this genetic feature, the HLA-DR4, then you had lower levels of CD8 exhaustion. And so this was really exciting because it wasn't something we induced in a trial. It's a large study. It goes to predisposition of disease as opposed to something you therapeutically modulate with a drug.

So are we thinking then that like end goal is you exhaust a subset of T cells that are self-identifying and that's a treatment? And so you don't exhaust all T cells, that would be real bad, obviously. Yeah. You can do a targeted exhaustion of self-identification so that you need less exogenous broad spectrum immunosuppression because you can—

Exactly. Yeah. Yeah. And that is kind of the way the field's going. That's another step in the future to target things in an antigen-specific manner. That being said, I do think that type 1 diabetes is one of the autoimmune diseases where we know more of the antigens. So, we actually can move forward in that manner.

I'm interested about that because on the one hand, you're— what you said is that a particular HLA type in CD4 cells is associated with exhaustion in CD8 cells, or also you see exhaustion in CD4 cells in the context of type 1 diabetes.

Yeah, we don't see a screaming signal in the CD4s. So yes, it is a bit of a quandary that an HLA Class II molecule, which typically talks to CD4s, is dictating a CD8 phenotype. And so this is an association first, so let's not over-interpret. However, it was reproduced in a second dataset. And there is evidence in the literature that the lack of CD4 help can lead to CD8 T cell exhaustion. So, we need to design the experiments to ask these questions, but I would say that one probably leads to the second.

So, my question is, Tulsi, you talk— we know what are the targets of these T cells in type 1 diabetes. So, maybe— I actually don't know, what are exactly the proteins or the peptides that are being presented by pancreatic islet cells that are being recognized by CD8s? Are there specific antigens that pop up?

Yeah, there's some great work being done by people for a while now and continues in terms of identifying those antigens. So insulin, a lot of things, IGRP, GAD, Zinc transporter 8. I'm just throwing out some words here for anybody to kind of follow. But really, overall, there are many of the antigens or many of the proteins that are in the beta islet cells that are in the machinery of the granules that force the insulin molecule to be secreted. So, it's either the phosphatases involved in that process or the trafficking molecules, just any of those in those granules that are produced quickly and take a lot of energy to continually produce. In a beta cell and are identified as antigens. That being said, we're also seeing a lot of neoantigens very much in the cancer setting where, because the cells are working so hard to produce the insulin and maybe they're a little bit damaged, and so they're even working harder, they're spitting out some proteins that have misfolded or have alterations. And so, those have been identified as antigens also in type 1 diabetes.

So obviously you can get antigens because when you screw up a cell and make it die from an autoimmune reaction, then it releases particles which are then identified as they should not be there. And then you drive antigens to those. And those are really what I would call secondary or incidental antigens. They're not the cause of the disease, but they're a marker of it because why do you have an antigen? You know, like, like for instance, I don't think autoantibodies to insulin, or some of them are, or the intracellular phosphatase is probably what is initiating the type 1 diabetes. Because how would this immune cell ever encounter it internally? But then there's other surface markers. So of that list that you gave, which are the ones that we think are pathogenic, which may be separate from pathognomonic or secondary bystander molecules that your body's going to pick up? Like, why do I see this phosphatase as an example? Do we know which ones are the big ones other than probably not an intracellular one?

Great question. And I think I would even say that it could be some of the intracellular ones. As a protein that's made in the pancreas, we kind of have to live— learn as our body has to learn how to ignore it. So, it is recognized in some sense to know not to respond to it. And it might be that form of tolerance that's lost. I don't think we know. And it actually differs from individual to individual. And in fact, even there's some type 1 diabetics that get insulin antibodies first, and they tend to be younger and more aggressive with disease. There are people that tend to have GAD antibodies first, and those are people that are a little bit older and have a little bit of slower disease. So, there's some suggestion that the antibodies are doing something different, but what that is and why they recognize at different times and what that sequence is, really has not been well parsed out quite yet. Yeah.

Real quick on the phosphatases though, are the phosphatases secreted phosphatases or ones that are just like an intracellular phosphatase?

Intracellular.

Right. So yeah, it's interesting how they— that would ever be detected by an immune cell unless the immune cell attacked that.

Well, I mean, they can be presented on MHC peptides derived from these. If they're very abundant in this particular cells because they need them a lot, they're going to be they're going to be more proportionally more presented on the surface of the islet cells and other cells that just have a little bit of this phosphatases. So they don't— they have fewer molecules on their surface, I guess. And yeah, sorry, I just want to say—

of the field too, we sit here and create all these things.

It's all about TCRs. Yes, the TCRs they see inside the cells. They don't need—

I mean, true, but simultaneously you don't present everything in its own.

They have magical eyes. They see inside what's going on under the hood. That's why it makes it— that's what makes it so special. And talking about special cells, I have kind of related to this conversation. Do we know— so you, you're aiming— so going back to the T-Rex, and I'm sorry, but I just need to ask, going back to the T-Rex and their potential as a therapy for type 1 diabetes. Are the Tregs— do we know whether those Tregs that are protective and that we want to maybe modulate, are they also recognizing antigens that are kind of islet-derived? Do they also have specific antigen recognition that we have identified by now?

Yeah. So people have studied Tregs in type 1 diabetic subjects and also mouse models where there are Tregs that recognize islet antigens. Yeah. And that knowledge is being used to kind of think about how to make the best Treg and provide that for somebody who would only attack the beta islet cells.

Hmm.

I like that.

There's a lot of potential. There's a lot of people doing exciting work in both of the fields of exhaustion and Treg regulation.

So does there— do you think there's the potential overlap? Or again, like if you have, if you have type 1 diabetes in a model, is the Treg trying to stop the inappropriate reaction? And maybe in like, I don't know if you guys looked at sulfate, like people who get type 1 diabetes don't have Tregs due to this islet cell protein. And people who do get type 1 diabetes are missing that Treg, like, like the lack of a specific Treg to an islet cell is indicative that you'll get it?

Yeah, we haven't found that quite yet. My sense is the data would argue against that hypothesis. I just study humans a lot. There's a lot of heterogeneity in people, and I would expect the antigens to be different across many people, but I don't know. It's a good question.

It might be really hard also to follow people that at some point develop diabetes, but you don't know what happened. Before that. So, and also usually it's early when they're early on in life. So yeah, you don't have a lot of— you're not going to be sampling people randomly to see if all of a sudden they lose the T-rex around their eyelids and that precedes their development of diabetes.

But that being said, there are a lot of really nice longitudinal studies that are being designed because people see the need to do that, and they'll be a lot of consortiums like TriNet or many of the European consortiums that'll pull people in if you have a relative, and you will be—

Mm-hmm.

—screened and followed. So we can study that and ask those very precise questions because otherwise there's no other way to find that. I think one of the challenges is to marry the cohort collection, which is a challenge in and of itself, with the newest of technologies to run on those cohorts. And so those are— it's kind of a balanced walk.

And then you get the cohorts, but the way the cohort's running, but it's not set up for what you need with the newest technology. And so how do you catch up to that and then modify the cohort collection process so that you preserve the cells this way or that? Yeah, it's a constant— I imagine it's a constant arm race. You see it like the Framingham Heart Study is really famous. That's been going on forever. Keeps getting updated to like be useful now. Yeah.

Which is exciting actually. It's fun to see the process. Yeah.

So to kind of wrap up this section then, so it looks like you were saying we're hoping for a new drug for type 1 diabetes soon, but that the, that the Treg is still kind of around the corner. Where do you see the field going in the next few years in terms of Tregs and diabetes? Like, what's the hot question the universe is driving towards answering? Or if there is one.

Yeah, I think it actually is the therapeutic question, which is why there's multiple avenues of people moving forward in that realm. So I do think we'll see some trials in the next couple of years. Whether they're approved, which I think is what you were asking earlier, is a little harder. There's a lot of basic biology that we still need to understand. About Tregs, how to maintain their function, how to augment their function. I think there's a lot of effort in that realm also. That would spread all the way from really basic studies with mouse and biochemical experiments all the way up to human trials.

I really hope that immunotherapy for type 1 diabetes will be reached at some point. I work in the cancer immunotherapy field, and it just makes sense that if the immune system is broken, you know, you should fix that. And that would be— but of course, we need to understand best, better, what is that it's working poorly and then focus on that. And I think Although we're very early stages, this modulation of the good guys, kind of increasing the function of the good guys and exhausting the bad guys, seems like a good starting point for a future in immunotherapy of type 1 diabetes in particular and many other— of course, there's many other autoimmune diseases. I guess that Do you think some of what we learn in the case of type 1 diabetes also applies for, as you mentioned, rheumatoid arthritis, for example, or other— well, I don't know, MS, things like that, that are, yeah, devastating autoimmune diseases? What do you think is the most important shared topic that you as a researcher in this area think about? Yeah.

Most shared topic, I think it is regulation because that's what we do want to do and do it well early so we can prevent the destructive and chronic nature of these autoimmune diseases. Because a lot of the research, once you get into more severe disease, is a much harder balance where you're trying to correct the immune system, but at the same time trying to regenerate and fix the target organ, whether that's the pancreas, the brain, the joints. So it's a little— a few more— a lot more moving parts to fit. So once— yeah, I am also hopeful that we're gonna get this regulation thing kind of figured out maybe in the next 10 years. I don't know if we'll have anything approved in a single autoimmune disease by then, but definitely tested in trials.

I'm sure you and Alice here could talk about Tregs all day, Brenda, because I know just how close they are to your heart. But we sometimes have to move on. And so we're going to wrap this up. We always want to ask kind of a fun question to end things up. So for you, Alice, if you had to do a hobby that did not involve T-cells, what would it be? And you know, you've not had time to do this hobby because of all the T-cell work. What would it be and why?

Yeah, so I do this a teeny bit on the side anyways, but I would do some ceramics. I would throw pots. What type?

Do you do like vases and then all your friends get a ceramic vase for their birthday? Or are you doing some, uh, some nice and functional? Or very— what's your style? Do you go very bold on your designs, or it's more like something functional that, you know, might actually have a use.

Yeah, something in between, because the use one is hard. I'm not good enough quite yet to do that, so I don't like to give those to people. But if you could do something that's a tiny bit functional, but you make it quirky or just kind of give it a fun nature or a lot of color with the glazes, then that makes it a lot of fun and a little less pressure to be something that really works well.

No holes in it, right? Right.

Exactly. Here's a vase for your flowers, like, but it has a hole in the bottom. Well, you know, that's where it was stuck to the rotating machine for the ceramics. That's nothing I can do about it, but I do hope you will use it.

Well, thank you very much for coming on. And it's been a pleasure here with all the stuff going on at AI to get to talk to you.

Yeah, I hope you enjoyed, and I hope all our listeners enjoyed, those who could attend enjoyed the meeting. I think it was very— it was nice to see people in person again. I mean, things actually physically.

Well, again, thank you very much.

Yeah, thank you.

That brings us to the end of our show. Don't forget to subscribe to our newsletter at www.immunologypodcast.com to get the show notes, including an episode summary and links to all the interview and roundup papers. You can also reach out to us on Twitter at @AminoPodcast or via email at info@immunologypodcast.com with feedback or suggest guests. See you next time.