non: [00:00:00] You are listening to the ATS Breathe Easy podcast, brought to you by the American Thoracic Society.
Erika: Welcome to the ATS Breathe Easy podcast. This is our series on what you may have missed at a S 2025. I'm your host, Dr. Erika Moses. A pulmonary and critical care medicine physician in Portland, Oregon. And I'm here with Dr. Adam Soof of the University of Pittsburgh, who's presenting his work here titled Inhaled Microplastics, inhibit Tissue Maintenance Functions of Pulmonary Macrophages.
And he will be presenting this at the ATS session. Macrophages, the Pac-Man of the Immune System.
Adam: I, I did love that. I thought that that was great. 'cause that's, I will describe them to my family as the pacmen, you know, around BBBB.Butso why don't you
Erika: tell us about yourself and how you became interested in this topic and how you became an immunologist.
Adam: Yeah. Somy name's Adam [00:01:00] andI've been an immunologist since I was, you know, a young scientist.And I've been interested in pulmonary immunity, right? And particularly macrophages, how macrophages respond to our environment. So kind of all the environmental exposures minus cigarettes, right? And particularly how those exposures can epigenetically tweak.
Mal adapt, regulate our macrophages, right? So. The story we're talking about today is on microplastics. And I have to be completely honest, this was not something on my radar as of like a year and a half ago, we were studyingmilitary exposures like burn pits on the veteran side. On the university sidewe look at sex-based differences, so femalesyoung women who are getting lung cancer at increasingly high rates.
No one knows why. Right. So to me, immunologist, it's gotta be immune mediated.Probably the max. 'cause they're the most important cell. As an immunologist, you have to pick a favorite cell. Like it's, it's part of getting your, and your part. Yes, [00:02:00] definitely. And they're PAC men. Right? So we were looking at sex-based differences and I, I'm a PhD, so I'm a lab rat and I jokingly refer to myself as a buddy, team, lab rat.
And a cutter, well, my cutter a surgeon, cardiothoracic surgeon, Raj DUP Par is amazing. If you ever see him, give him a big hug, give him garage. He's a wonderful human being. He got interested in this and he brought it up. He goes, microplastics, you know, what do you know about 'em? I'm like, I don't know.
They're in the, they're in the fish, they're in the water, you know, bad news. So we, he really started pushing. He's like, we should look into this. This is an exposure that's everywhere. And what do you know about it? What do we know about it? And so begrudgingly, I'm like, okay, well let's, let's run some experiments.
Let's get some plastics. Let start checking it out. And we've already been doing this on like diesel particulate, PFAS, different chemicals, PM 2.5, things like that.So it was just adding another to the mix kind of. Right? And every step of the way when I'm like, these are gonna be boring. Like whatever, man, plastic, they're inert plastic, right?
[00:03:00] Macrophage eats it, it goes away or something. Right? And every step of the way, it wasn't. Right. And so I time and time and again in the lab I'm like, Raj was right. And we keep on going with this. So as we've built up steam, we've gone from cells, mouse cells to patient cells, toin vivo mouse exposures.
Now we're looking at our patient lung tissues. We have a microarray of about 180, 190 patientslung cancer. And so both the tumor and the paired, and we're examining that for exposure. And I am begrudgingly convinced that these things are uniquely bad in a way that we haven't appreciated. And I told you I worked it.
I, my little brother then calls me the Lorax of the thorax because, you know, I'm speaking about this, you know, basically this ever present, you know, ubiquitous threat that we all live with and that we don't understand. So
Erika: absolutely. How do you define. Microplastics, like I think we all have an idea of what they [00:04:00] are.
Right. But how do you define them from a research standpoint? Under understand when you've like found them. Yeah. Under, you know, researching them. You know,
Adam: so in my house, anything small is, you know, plastic is bad. Mm-hmm. So you take the old shavings. To me, I'd consider that like, technically a microplastic is under five millimeters and a nanoplastic is one micrometer or smaller.
Right.So we get lots of that. So you think about, I mean, when do you ever get a plastic that was actually made, you know, they can call primaries, so they're made for certain purposes, but normally it's, we get these plastics 'cause things are breaking down, right? So you have your water bottle, you have your baby bottle, you have plastic bags, you have PVC piping, everything we touch, like, I mean, so much of it, right?
So that gets. Rubbed against, or it gets UV light exposure, it getsso physical disruption, chemicalbiodegradationdegradableso bacteria can eat things. I. So what you get is these smaller [00:05:00] particles, and that's one bit of the problem, right? Like our body doesn't need foreign particles in it, right?
I don't think, well, not like that.And then the other bit is that they're not just inert. Like originally I thought the same thing, whatever, little plastic balls, right? But they're not, they absorb all these chemicals. Some are from the manufacturing process. So things like phthalates and, what is it?
Not the BPA, butand then toxins.Toxic heavy metals. They can regulate estrogen. They can disrupttheir neurotoxic, their carcinogenic. So now you have these little particles, which that's one thing. What does that do to our system? But now they're bringing in all these chemicals, and that's a completely different one.
Right. So kinda as
Erika: carrier particles, like we worry that PM 2.5 sometimes can be particulates can be carrying other things into our lungs when we inhale them.
Adam: That's exactly it, right? So they have hydrophobic and electrostatic interactions. They bind these chemicals. So now it's not just that little plastic ball, but it's the plastic [00:06:00] ball coated in carcinogen.
And that's in your gut. That's in your lungs. That's on your skin. I know it's terrifying,
Erika: isn't
Adam: it?
Erika: And so what do we know? So we're here at American Thoracic Society, obviouslywith the Lorax of the thorax. I'm very interested in our lungs and everything, but you mentioned working with a cardiothoracic surgeon.
So what do we know about how microplastics affect human health in other organ systems?
Adam: So little. Right. And I think the. The most established evidence now is in the cardiovascular world, right? So they found evidence of plastics and atherosclerotic plaques. They're in the macrophages
Erika: go max
Adam: in the atherosclerotic plaques.
They're trying to
Erika: protect us and they're trying to eat 'em, but they, they're just choking to death on those little plastics. Is that what you think? They are?
Adam: They are. There's actually a phenomenon. In tattooing where the tattoo pigment goes in the macrophage, eats it right, and then becomes basically anergic and then dies, and then another macrophage eats it to try to, you know, it's continually like throwing yourself [00:07:00] on a sword.
They're just trying to save you. Oh. So I think that that might happen in the plaques too.But they foundplastic loading laden max in the plaques. Um. And that that has been associated withworse outcomes. Now that's about the best clinical evidence that we have. And even that, you know, you can raise, I think it's an awesome study.
Butthere's, and worse outcomes like heart
Erika: attacks, strokesor cardiovascular perfusion sort of thing, all cause mortality. Right. So drop dead. That's pretty bad. Yep. Yep. But I mean, these were,
Adam: these were individuals who already had disease. Yeah. Butyou know, of course further study needs to be done.
Um. So, and what does it mean for lung? So there have been studies that found, you know, microplastics, nanoplastics inlung tissue in broncho, velar, lavage and sputum. They found it in colon, breast milkplacenta, liver, you know, I mean, everywhere. If you've, if you look, you're gonna find it there. Yeah.
Right. What does it do? Deal.
Erika: Well, yeah, I mean, that's interesting. You know, [00:08:00] it's reminding me of the studies where we look at, you know, black carbon inhaled, and you can look at the, you know, the cells in the lungs and look at clinical outcomes, you know? Yeah. Where you see that kids who living closer to a freeway have more of it, and then they're more likely to have respiratory complaints.
It's giving me chills that we maybe finding it another threat to our health. Oh, gosh. So in the air we breathe.
Adam: I, that's, that's really, so as I'm, you know, again, slowly becoming convinced of the impacts. Right. The epidemiology. And when I think about cancer, right? So one of the big, you know, I mean to me this major question, or maybe the biggest question in my mind is why are young people getting different cancers?
So young women who don't smoke getting lung cancer, young people getting colorectal cancer.Breast cancer is up in younger people, right? So this is too quick to be a genetic thing, right? Um. So what I wonder about obesity, totally. Obesity, lifestyle, sedentary things, but what other, what other factors?
And it's global. Mm-hmm. Right? So, you knowcountries like [00:09:00] Japan seeincreased incidents in younger people getting cancernot quite the sameepidemic of obesity that we have, right? Mm-hmm. So why, right? I, I have two theories.One is the internet. Right is that we are all, and not like the Internet's like freaking out our brains and we're like giving us cellular cancer, right?
Mm-hmm. But we're just stressed. Right? Okay. And we're like constantly on. I'm checking emails, which affects our immune system. Exactly. It's got it. Those max are stressed and they're not doing their job. So I think that that might be a, our connectivity and our pace of life. Mm-hmm. And that is something that's new.
Mm-hmm. But plastics, they were developed in the early 19 hundreds. They became common after World War ii, like 1945. Oh, the fun facts for the talk, right? Mm-hmm. We produce 450 million tons of plastics every year. That's as much as every adult human on earth ways, right? Wow. So we pump that out every year.
It's something like 7 billion tons since we've been making plastics, and 80% of [00:10:00] that. Still here, it's accumulated in the environment. Right? So now we're talking about an exposure that's increasing and it's happened since the forties. So now you get young people, higher doses, dosed from conception. You know, you're intrauterine.
Yeah. You're a little baby in placenta, right? Yeah. You know?So now you have these exposures, which we didn't have a hundred years ago. Yeah. Our grandparents wouldn't have had these exposures. Yeah. Is that the smoking gun? Like, I have no idea. And at first I, again, skeptical and it's good to be skeptical as a researcher, right?
Like you gotta be like that's,
Erika: but now you just walk around paranoid about the air you breathe. Yeah. I mean,
Adam: I have a, instead of my plastic bubble, I now have a glass bubble that isn't where steel that I roll around. So why
Erika: don't you tell us about your study that you're presenting here at ATS and what you found.
Adam: Yeah.So terrifying. Yeah. So we've. We usedpolystyrene, microplastics of different sizes, so 10 microns, so these would be, that's still a microplastic, but very small [00:11:00] down to 0.02 microns.We wanted to see what they did to macrophages, mouse macrophages, and human macrophages. We wanted to see what they did in vivo.
I will preface that these are not what we. Get exposed to in life. Okay? Right. This is a very controlled, the reason we went this route is they're fluorescently labeled, so it makes it very easy to tell this plastic from the one that's in my pipette tip or that's in the cell culture plate, right? So it, it made for a nice, clean starting point for experiments.
What we find isso the macrophages can't break apart the plastics. This goes back to them being a nerd. So you can put them in different acidic environments, does nothing. The lysosome does nothing, so they concentrate. Right?We believe this leads to a phenomenon called Frustrated Phagocytosis, right?
The max entire reason to live is to eat and digest things, like that's what it loves. And if it. Eat something and it can't digest it. That's like an existential [00:12:00] crisis for this macrophage, right? So it freaks out and it makes reactive oxygen species. It pumps out inflammatory cytokines and eventually it dies.
And that's what we're seeing, right? So we did an in vivo experiment andit's not the cleanest we did intranasal. So we can't rule out that these plastics don't go sum to the gut through the esophagus, right? Right, but intrad cell delivery of one micron plastics, the reason we went small is because like PM 2.5, we know that a particle of that size can go right through the alveoli, get into the circulation.
Right? So we put in thesefluorescent microplastics 30 million, which sounds like a lot, but it's about the size of a quarter of a grain of sand. Mm-hmm. Into a mouse, right? Then we looked at. The lungs, the liver, the kidney, the heart, the spleen, the colon, the brain. That was horrible. I'd never wanted to take brain and I had to learn to take brain.
So we looked at all these tissues and sure enough, we see tons [00:13:00] of deposition in the lung up to a week, right? Mm-hmm. So one day, three days, one weekit's still there. It's both intracellular and extracellular in the tissue environment.But the, the terrifying bit is we found it in the brain. And we found it in the colon and we found it in the spleen and liver.
We found it everywhere we looked and just to double check, we did, you know, flow cytometry on these tissues for the fluorescent particle. We did microscopy to fi identify these particles. So like, yeah, you know, one way or another putting this stuff in the nose. Got to the brain, putting it in the nose, got to the colon and the liver and the heart, and we started modeling that inprecision cut lung slices.
From our patients, right.To look atcan we regulate this? Oh geez. That might be the most exciting thing is part of the damage is bioenergetic. Right? So the microplastics decrease mitochondrial mass, they decrease mitochondrial function. Mm-hmm. And we can revert that. Hmm. So we found that if we [00:14:00] add an A MP activating.
Agent. Right. Which is commonly used in psych and doping. Okay? So, you know, bioenergetic is a pretty good thing, okay? But if we add this, we can actually resuscitate the max postor during their plastic exposure because it just boosts their mitochondrial function. So now they can wound heal better and they can eat and digest things again, not perfect, right?
But so, I might have to run a trial dosing humans with. Doping agent. I don't know. I don't know how we're gonna do that. We we're still working on that. We're still, and
Erika: they'll bike like crazy. Yeah. Right. So how many people inhale microplastics in the world? Is this just out in all the dust? Are there things you can do to.
Decrease it or is it just out there?
Adam: So yes. Right. It's just much like PM 2.5 smaller particles are gonna be aerosolized, so there're gonna be things that you just breathe in the wind.There are alsomicroplastics that are shed on by our clothes or when we're doing laundry [00:15:00] or. Your face mask has microplastics, right?
I don't have a face mask. Oh, well if you had a face mask put on your mask saying Surgical mask, a face mask, surgical face mask. Surgical mask. Right. Oh yeah. That's. So how do we, I think what I've started doing is just being mindful mm-hmm. In my environment, like my water bottle's metal. Mm-hmm.I have thrown out thosetakeout containers, which I love to use at my house.
'cause you know, they're easy for kids and things like that. Yeah. So now no plastics. Mm-hmm. So making some of those, the cutting board is now wood. Mm-hmm. You know, things like that, that, but what can we do? I meanyou stay outta dust storms.
Erika: I
Adam: don't know what we can do yet. I really don't. And maybe, you know, part of it's, can we identify the magnitude of the problem or mechanistically on the cellular and physiologic level?
What can that inform mitigation strategies? You knowI, I think ultimately this could be more of a public policy [00:16:00] intervention that needs to be made. Um. So,
Erika: yeah, just moving away from having plastic everywhere. Yeah. I'm
Adam: not holding my breath for that one.
Erika: Yeah. Yeah. So well, we'll see. Sometimes there's a lot of hope in state and local action when you know.
Yeah. People are skeptical of other interventions. You can kind of come together as communities potentially. Yeah,
Adam: and actually I'm, I'm kind of encouraged by some of the industry actions mm-hmm. To make plastics that are, you know, biodegradable that break down. Mm-hmm. So the old, the first generation plastics broke down over centuries.
Mm-hmm. So now, like we're years to decades, like, yeah. You know, but it's a, it is a huge improvement. Right. When you think about 80% of the plastic that has ever been made by humans is still here.
Erika: Yeah.
Adam: Like it's really scary. Totally. So,
Erika: So obviouslythis is a study in cells, but we touched on this a little bit.
So it sounds like it's, even though it's, we're still kind of at the cellular and tissue level, it's really made you rethink your own life changes. Is that right?
Adam: Yeah. Yeah. AndI think, you know, when, when we started studying [00:17:00] environmental exposures, their influence on pulmonary immunity. You know, I, I did consider, you know, well, we have those wildfire days mm-hmm.
In the states, you know, I don't mind wearing a mask. Mm-hmm. You know, I, it's one of those things like, should we be introducing this more into our, our daily routines? You know, I'll, if I'm concerned, I'll send the kids out the door with masks, things like that. Mm-hmm. Right. But, and trying to limit, you knowlimit exposures to plastics.
I was psyched. I went an electric car. That was pretty awesome. You know, I dunno what that does too much, but Yeah. You knowso yeah, I think making these, and we, we make our small, small changes. Yeah. As I said, when I got on a plane and came from Pittsburgh to here and I'm like, oh, everything I just done was undone.
Yeah. You know, but making small lifestyle choices, I think is our immediate way to protect ourselves, our loved ones, our community. Um. Yeah. And maybe that that gains momentum and Yeah. You know,
Erika: and I think, yeah, just [00:18:00] notlike just being okay with it's okay to learn new things and change as we go along in life.
It's not that, you know, everything has to have been set the way it was when we were children.
Adam: Yeah. Yeah. We can make things better. I think about the great advantages in plastic. Mm-hmm. Right? I mean, we go into the lab just having the convenience of, you know, contaminated and infectious samples and things like that, like so.
We, it, we have to learn to better live with the good parts and the bad parts and make those changes. Right. Yeah.
Erika: And kind of understand it's, that's why the science is important to actually understand the risks and benefits so you can scale your response rather than just freaking out about everything.
Yeah.
Adam: I'm still freaking out about everything.
Erika: I know. Exactly. Well, that's not healthy. It stresses out your macrophages. I heard. I know.
Adam: You know, it seems 2025 hasn't been a great year. Should not freak out about everything. So,
Erika: wellthank you very much for your time and your science and everything.
Is there anything else you wanna add?
Adam: No, I just, it's been a pleasure. Thank you for sitting down and talking to me.It's wonderful opportunity and I [00:19:00] love the ATS. I'm excited to be more a part of it, but thank you. This is terrific. Yeah, of course. Well, thanks for being here.
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