Episode 50: From Foe to Friend: Could common skin fungi be harnessed to heal the skin barrier?

skin fungicradle capadolescencedupilumab facial redness

Oct 15

Written By Global Parents for Eczema Research

Is everyday skin fungus playing a bigger role in eczema than we ever realized? What if the culprit behind cradle cap, dupilumab facial redness and eczema flare-ups in puberty is hiding in plain sight, on the surface of our skin? Professor of Fungal Immunology from University of Zurich. Dr. Salome LeibundGut-Landmann, explains the secret world of skin fungi, how it affects eczema and a bold new project to convert fungi into skin helpers. If you like our podcast, please consider supporting it with a tax deductible donation. Read the transcript.

From Foe to Friend
Lynita: [00:00:00] Hello did you know that a simple condition like cradle cap, the flaky, oily patches that many babies get on their head could hold important clues about eczema? Cradle cap is caused by a common skin fungus, and studies show that babies who develop it are far more likely to go on to have eczema. In fact, one Greek study found that 60% of infants with cradle cap later develop the condition.
We see hints of the connection between eczema and fungus, again in Dupilumab users. Some [00:01:00] people on Dupilumab notice that their eczema clears everywhere except the face once they start treatment, doctors call it dupilumab facial redness. And although the phenomenon is not fully understood, it tends to only affect people following puberty when the skin oils increase and fungi thrive. What's more, a study from 2021 found that treating facial redness in dupilumab uses with an antifungal cleared the skin in. 10 out of 13 people studied, which again points to fungi being the culprit.
So could an everyday skin fungus be playing a bigger role in eczema than we ever realized? What if the secret culprit behind cradle cup, dupilumab, facial redness, and eczema flare ups in puberty is hiding in plain sight: on the surface of our skin?
If, like me, you're worried about what puberty might bring for your eczema child, or you're considering dupilumab and want to know more about how fungus affects difficult to treat [00:02:00] eczema, then this episode is for you.
In this episode, we'll explore the hidden world of skin fungi, how they may be making eczema worse, and an ambitious new project to convert them into skin helpers instead.
This podcast was recorded in July, earlier this year.
Lynita: Welcome to the Eczema Breakthroughs podcast. There is a lot of talk in eczema circles about the skin microbiome. The microbiome consists of anything living on our skin, including fungi. Some fungal infections we are more familiar with are athlete's, foot thrush or ringworm.
But today we are going to talk about a group of fungi that might be more important than we realized in exacerbating eczema. It's called Malassezia.
Joining me today to explain all this is Dr. Salome LeibundGut-Landmann. She is a professor of fungal immunology and hails from Switzerland, where for the past 15 years [00:03:00] she has been leading the fungal Immunobiology lab at the University of Zurich, but hot off the press.
She will now be also leading a team of multidisciplinary researchers based at the University of Exeter in the UK, who have been awarded a five year research grant to study how Fungi drive eczema with the goal to find better treatments and a potential cure. Dr. LeibundGut-Landmann, welcome to the podcast.
Dr. LeibundGut-Landmann: Thank you very much. Thank you for having me.
Lynita: We're really pleased to have you here, Let's start with the basics, though. Can you please tell us, what is Malassezia?
Dr. LeibundGut-Landmann: Well, as you've alluded, it is a fungus. It's actually a yeast, so a yeast as we know, baker's yeast, brewer's yeast, of course a little different, but very similar still. It naturally lives on the skin, and there it lives in close interaction with bacteria and of course, the skin itself.
It is a particular yeast in the sense that it loves [00:04:00] lipids. So it's probably mostly found in the hair follicles where there is lots of lipids, in the sebum, and also in a way it's protected from us showering, rubbing the skin, et cetera, because it's really stable. It stays with us from shortly after birth until the end of our life.
Lynita: So when you say that Malassezia loves lipids and sebum, so they like the fats that are on our skin. And it finds nice places to live, in our hair follicles, which are like the little divots in our skin where the hair comes out and there's a bit of lipids or sebum in those areas. And it can hide in there and it doesn't get washed off so easily,
Dr. LeibundGut-Landmann: Exactly.
And while it's usually really harmless or even helpful for us and our health it also can have, under certain conditions, harmful consequences as in the case of eczema.
Lynita: Okay. Our skin is supposed to be our defense system. Why is it that [00:05:00] Malassezia might be a problem for eczema skin? Is there something that healthy skin can do that eczema skin can't do?
Dr. LeibundGut-Landmann: Yes. Let's talk about what the situation is in the healthy skin, where usually fortunately things work well and Malassezia doesn't bother us. So indeed the skin has various layers of how it protects itself from Malassezia as well as other microbes that live on our skin. In the first instance these are the skin cells themselves. They form a tight barrier, like a wall of bricks where the bricks are really tightly joined. And Malassezia cannot enter in the healthy skin.
And in addition, these skin cells also produce some molecules that act a bit like natural antibiotics, and they also prevent Malassezia from overgrowing. And then on top of that, built in into that brick wall, we have a whole plethora of immune cells that produce cytokines, such as, interleukin 17, [00:06:00] which is also very important for reinforcing this brick wall and making it tight.
Interestingly, these defenses are really critical for keeping Malassezia in check in the healthy skin, but they do not eradicate Malassezia. They make sure that Malassezia stays with us, given the fact that Malassezia also has beneficial effects to us on our skin.
Lynita: Okay.
Dr. LeibundGut-Landmann: But then the whole skin makeup in eczema skin is altered, you can imagine, has little holes which allows a bit of access, but also these immune cells reacting against Malassezia are of a different sort. And so instead of producing interleukin 17, which usually reinforces the brick wall, they make different cytokines that drive the allergic response like the itching, the inflammation, that further exacerbate this whole vicious cycle in the end.
Lynita: That was a really great explanation. Thank you. So eczema skin is [00:07:00] more open to allergies because it’s producing less IL or interleukin 17 and therefore the healthiness of the skin in eczema patients is less robust,
Dr. LeibundGut-Landmann: Yes, and in some eczema patients Malassezia is different, especially in lesional areas. The skin becomes more sensitive and also easily irritated by substances that are normally harmless, right? And, many of these normally harmless substances are pollen or house dust mite, but in some eczema patients uh this reaction can also be against Malassezia. And, also drive the allergic response in eczema.
Lynita: So there's two things going on here, one, how our skin, defends against Malassezia entering the skin and two, how antibodies bind to the Malassezia and can create an allergic reaction,
Dr. LeibundGut-Landmann: Yes.
Lynita: Ah, how frustrating. And so Malassezia lives on our skin from soon after we're born. in [00:08:00] most healthy skin it's not causing a problem, but in some people with eczema, it does cause a problem and it interacts with the immune system. But not everyone, that's the interesting thing.
Dr. LeibundGut-Landmann: Exactly. And that's also the big conundrum: why in some and why not in others.
Lynita: Sure. This is another thing for parents to think about. At the moment they think about dirt and dust and pollens on their skin, and Staph aureus because it's well talked about. But now we've got another thing to think about and that's Malassezia.
So let's just go through some common practices and how that might affect Malassezia?
So moisturizers we put on eczema skin,
Dr. LeibundGut-Landmann: Well, moisturizers are meant to repair the skin this broken wall of bricks and make it tighter again. And this would also help to keep Malassezia on the outside of the skin where it's usually belongs. And this should help to prevent Malassezia from driving inflammation and itching. So that would be also helpful.
Lynita: Good. What about steroid [00:09:00] creams? Is that gonna have an impact on Malassezia?
Dr. LeibundGut-Landmann: Steroids are very broad anti-inflammatories treatments, right? Steroids, dampen inflammation, and thereby generally reduced symptoms of eczema. And this of course then also includes the repair of the cell wall and the readjustment of the immune system.
And although, it's not known to my knowledge whether that would directly affect Malassezia as a whole, they will also contribute to Malassezia being more helpful than harmful.
Lynita: Okay. That's also good. Another thing that's often put on skin of kids with eczema is antibiotics because they're trying to control Staph aureus. Would that affect it?
Dr. LeibundGut-Landmann: I am not sure there are data out for skin, but one important thing to realize about antibiotics is that they target the bacteria. And as such, by reducing the bacterial load on our skin, they will make more space [00:10:00] for other things such as fungi, because antibiotics are not active against fungi. So are they not active against Malassezia. And as such, there is a risk, let's say, but I don't know of any data, but there is a certain risk that by giving antibiotics, if we don't combine them with antifungals, that we would allow more space with Malassezia. And if Malassezia is in a status where it actually exacerbates eczema rather than protects us from eczema, this may actually not be so helpful in the end.
Lynita: That is interesting. Putting bleach very dilute into baths is another common practice to try and clear the microbiome. Same situation, do you think there?
Dr. LeibundGut-Landmann: Well, not exactly as the antibiotics, because this is you know meant to act, let's say, similarly against bacteria as against fungi. And as such it should also diminish the load of Malassezia on the skin, which may be [00:11:00] helpful, especially, if we have harmful Malassezia in our skin.
Lynita: Cool. Antifungal cream. Would that be beneficial?
Dr. LeibundGut-Landmann: Actually this is, especially in those patients with head and neck, eczema, which is the form of eczema that is associated with Malassezia actually there are guidelines now by the dermatologists which recommend antifungals to treat those patients.
Lynita: Okay. So it might be an avenue worth exploring if, other things are not working
Dr. LeibundGut-Landmann: Yes, absolutely. And especially in those patients where there is good evidence that targeting Malassezia may be beneficial.
And maybe I can make a link back to also what we hope to achieve with our project. So these guidelines recommends to treat with antifungals, which is of course a broad antifungal. So that would reduce Malassezia and all other fungi or skin very generally. But given that Malassezia [00:12:00] has also some good effects on our skin, we hope to find a way how we can more specifically reach the bad guys within the population of Malassezia and leave alone those that help protect our skin.
Lynita: Okay. What about sweating? Because a lot of people complain that their kids run around and they get sweaty and their eczema gets worse. Could there be a link between sweat and the growth of Malassezia on our skin?
Dr. LeibundGut-Landmann: Not to my knowledge that this has been looked into. Certainly an important component of sweat is the high salt content, so another area where we definitely need more research and I can't say anything at that stage.
Lynita: No worries. Um, My next question is, can Malassezia create an environment that is more conducive to Staph aureus?
Dr. LeibundGut-Landmann: Absolutely. but again, this is an area that is a very under-researched and as such, there are several possibilities, such as including, if [00:13:00] Malassezia contributes to making little holes in the wall of bricks, or in the skin, that will also allow better access for Staph aureus, for instance.
There are some other elements which are quite interesting because they actually point in the different direction. So there is also evidence that Malassezia would actually counteract Staph aureus. It can destroy clusters of Staphylococcus aureus cells growing together and Malassezia would kind of separate them out. And in that sense, be beneficial and contribute to more healthy skin.
Lynita: So I'm really hearing that Malassezia has a very complex relationship with our skin and in some situations it's really giving us an advantage. It might be helping control Staph aureus, but it is better at doing that on healthy skin than unfortunately on eczema skin.
So I guess therein lies the, the balance that I'm hoping you guys will be able to [00:14:00] give us more answers to, I guess, over the next five years.
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Dr. LeibundGut-Landmann: I hope so too. That's a very nice way how you summarized what I was saying. Yes.
Lynita: One of the background reading I did said that Malassezia abundance can be lower on eczema skin and particularly on lesional skin. And that just seems completely opposite to what we've been talking about. Why would this be?
Dr. LeibundGut-Landmann: This is actually quite a controversy in the field and indeed this has been reported. Most of these studies which look at Malassezia abundance in the skin did not look at the subset of eczema, patients with head and neck eczema. But we now know that Malassezia is really linked to this head and neck form of eczema.
Lynita: You keep mentioning head and neck eczema. That type of eczema is more commonly associated with adults so do you think that the role of Malassezia in little kids is probably not as important?
Dr. LeibundGut-Landmann: It's good you [00:15:00] say, “I think” because we don't have enough data on the role of Malassezia in these different age groups. But it's very well possible that Malassezia is a bigger problem in adult eczema patients than in children.
Malassezia is on our skin from when we were born, basically. But it's there at relatively low abundance initially, then it's during puberty when the amount of Malassezia really increases. That's also when the whole skin changes, right? When it becomes more oily. And that's what Malassezia loves so much, all these lipids. And that's really when Malassezia becomes more abundant on our skin.
Lynita: Yeah. Thank you. Tell us about the new study that has been awarded and what you hope to learn.
Dr. LeibundGut-Landmann: Well, in this study, we really aim to better understand why Malassezia exacerbates eczema in some patients, but not in others. And so we really wanna understand what's [00:16:00] different in those patients. And what we hypothesize is that actually Malassezia is somewhat different in the eczema skin of those patients compared to Malassezia in other eczema patients or in healthy skin. And we hope by understanding these differences to also better understand how then Malassezia does make the immune system to respond different. We predict that with this knowledge about Malassezia and also differences in Malassezia, would allow us to readjust the skin's fungal community and to convert harmful Malassezia into harmless Malassezia, which might even benefit the skin.
Lynita: Okay.
Dr. LeibundGut-Landmann: We actually recently found in my laboratory that Malassezia can contribute also to fixing the wall of bricks.
Ideally, you know, if we can [00:17:00] find ways of converting harmful to harmless Malassezia, we might even make it help to repair the skin in eczema patients.
Lynita: That'll be a wonderful dream to take something that's been aggravating eczema and driving itch to something that strengthens our skin barrier.
All this research that you've talked about what do you think are the key takeaways for eczema parents?
Dr. LeibundGut-Landmann: Certainly, take care of the skin, moisturize it, and that will also help keep Malassezia in check and hopefully have it exert its protective functions rather than the harmful functions, which makes eczema worse.
And Look at the subtype, whether it's a head and neck form of eczema. And trained dermatologist with experience in eczema, can tell that part relatively easily. And in those cases, the choice of treatment may be adjusted with maybe antifungals.
And let's see, in a few years, I really hope that we'll [00:18:00] find anything that can further help those patients that suffer so much.
Lynita: Yeah! Well, thank you so much. I have really enjoyed the explanations that you've given of how our skin works and how it defends itself against Malassezia. And I think it helps a lot to understand that it's complex. It's good or it's bad. And it might depend really on how damaged your skin is. Or even having an allergic reaction to the Malassezia. So with that, thank you so much for your time.
Dr. LeibundGut-Landmann: Thank you very much.
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