- Inside the lab where killer fungi experts working to stop next global pandemic – after WHO warns four organisms ‘critical’ threats to public health Daily Mail
- Epidemic of severe infections of skin, scalp, and nails: Overuse of over-the-counter creams linked to antifungal resistance Genetic Literacy Project
- Killer fungi detectives: inside the lab that may be fighting the next pandemic The Guardian
- Synthetic Polymers Offer New Hope Against Fungal Infections Mirage News
- Aussie treatment could fight ‘big problem’ killing 3.8 million a year Yahoo News Australia
Tag Archives: fungi
Scientists discover that fungi can effectively break down plastic – Boing Boing
- Scientists discover that fungi can effectively break down plastic Boing Boing
- Australian scientists discover plastic-eating fungi Insider
- Plastic-eating backyard fungi discovery boosts hopes for a solution to the recycling crisis ABC News
- Australian scientists say they have discovered a backyard mold that can break down plastic in 140 days — giving hope to the recycling crisis Yahoo News
- Australian scientists say they have discovered a backyard mold that can break down plastic in 140 days — Business Insider India
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‘The Last of Us’ Come Alive: Fungi Are Adapting to Warmer Temperatures
Dangerous fungal infections are on the rise, and a growing body of research suggests warmer temperatures might be a culprit.
The human body’s average temperature of 98.6 degrees Fahrenheit has long been too hot for most fungi to thrive, infectious-disease specialists say. But as temperatures have risen globally, some fungi might be adapting to endure more heat stress, including conditions within the human body, research suggests. Climate change might also be creating conditions for some disease-causing fungi to expand their geographical range, research shows.
“As fungi are exposed to more consistent elevated temperatures, there’s a real possibility that certain fungi that were previously harmless suddenly become potential pathogens,” said
Peter Pappas,
an infectious-disease specialist at the University of Alabama at Birmingham.
Deaths from fungal infections are increasing, due in part to growing populations of people with weakened immune systems who are more vulnerable to severe fungal disease, public-health experts said. At least 7,000 people died in the U.S. from fungal infections in 2021, the Centers for Disease Control and Prevention said, up from hundreds of people each year around 1970. There are few effective and nontoxic medications to treat such infections, they said.
Photos: What We Know About Deadly Fungal Infections
In the video game and HBO show “The Last of Us,” a fungus infects people en masse and turns them into monstrous creatures. The fungus is based on a real genus, Ophiocordyceps, that includes species that infect insects, disabling and killing them.
There have been no known Ophiocordyceps infections in people, infectious-disease experts said, but they said the rising temperatures that facilitated the spread of the killer fungi in the show may be pushing other fungi to better adapt to human hosts and expand into new geographical ranges.
A January study in the journal Proceedings of the National Academy of Sciences showed that higher temperatures may prompt some disease-causing fungi to evolve faster to survive.
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Researchers at Duke University grew 800 generations of a type of Cryptococcus, a group of fungi that can cause severe disease in people, in conditions of either 86 degrees Fahrenheit or 98.6 degrees Fahrenheit. The researchers used DNA sequencing to track changes in the fungi’s genome with a focus on “jumping genes”—DNA sequences that can move from one location on the genome to another.
Asiya Gusa, a study co-author and postdoctoral researcher in Duke’s Molecular Genetics and Microbiology Department, said movement of such genes can result in mutations and alter gene expression. In fungi, Dr. Gusa said, the movement of the genes could play a role in allowing fungi to adapt to stressors including heat.
Dr. Gusa and her colleagues found that the rate of movement of “jumping genes” was five times higher in the Cryptococcus raised in the warmer temperature.
Cryptococcus infections can be deadly, particularly in immunocompromised people. At least 110,000 people die globally each year from brain infections caused by Cryptococcus fungi, the Centers for Disease Control and Prevention said.
Candida auris, a highly deadly fungus that has been reported in about half of U.S. states, also appears to have adapted to warmer temperatures, infectious-disease specialists said.
“Fungi isn’t transmitted from person to person, but through fungal spores in the air,” Dr. Gusa said. “They’re in our homes, they’re everywhere.”
An analysis published last year in the journal Clinical Infectious Diseases said some potentially deadly fungi found in the soil, including Coccidioides and Histoplasma, have significantly expanded their geographical range in the U.S. since the 1950s. Andrej Spec, a co-author of the analysis and an associate professor of medicine at Washington University School of Medicine in St. Louis, said warming temperatures, as well as other environmental alterations associated with climate change, could have played a role in this spread.
Cases of Coccidioidomycosis or Valley fever, a disease caused by Coccidioides, were once mostly limited to the Southwest, Dr. Spec said. Now people are being diagnosed in significant numbers in most states. Histoplasma infections, once common only in the Midwest, have been reported in 94% of states, the analysis said. Histoplasma is also spread through bat droppings and climate change has been linked to changing bat migration patterns, Dr. Spec said.
The World Health Organization has identified Cryptococcus, Coccidioides, Histoplasma and Candida auris as being among the fungal pathogens of greatest threat to people.
“We keep saying these fungi are rare, but this must be the most common rare disease because they’re now everywhere,” Dr. Spec said.
Write to Dominique Mosbergen at dominique.mosbergen@wsj.com
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Histoplasmosis Lung Infections Widespread Across the US: Study
An illness-causing fungus known as histoplasma is in the soil of nearly all U.S. states, a new study suggests. The researchers behind the work say doctors may be relying on outdated risk maps and therefore missing diagnoses of the infections, which can sometimes be deadly.
According to the CDC, histoplasma, or histo, is found in the soil of central and eastern U.S. states, primarily in Ohio and the Mississippi River valleys. But that assumption is based on research from the 1950s and 1960s, says the team behind a new paper published in Clinical Infectious Diseases. When a person breathes in spores of the fungus, they can contract an infection called histoplasmosis.
“Every few weeks I get a call from a doctor in the Boston area – a different doctor every time – about a case they can’t solve,” said study author Andrej Spec, an associate professor of medicine at Washington University in St. Louis, in a press release. “They always start by saying, ‘We don’t have histo here, but it really kind of looks like histo.’ I say, ‘You guys call me all the time about this. You do have histo.’”
Lead author Patrick B. Mazi, a clinical fellow in infectious diseases also at Washington University in St. Louis, and his colleagues analyzed more than 45 million Medicare fee-for-service beneficiaries extending from 2007 through 2016. They looked at diagnoses across the country of three fungal diseases: histoplasmosis, coccidioidomycosis, and blastomycosis. Histo, the most common, was causing clinically relevant rates of illness in at least one county in 48 of 50 states, as well as Washington, D.C. The other two infections were each found in more than half of states.
“Fungal infections are much more common than people realize, and they’re spreading,” Spec said in the release. “The scientific community has underinvested in studying and developing treatments for fungal infections. I think that’s beginning to change, but slowly.” Climate change may be driving this spread as warming temperatures make more habitats suitable for the fungi.
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While histo can be easily combatted in healthy adults, and many people who are exposed never develop symptoms, those who are immunocompromised as well as infants and people 55 years and older may develop more serious illness, including a cough, fever, chest, pain, body aches, and fatigue, according to the CDC. Symptoms appear within three to 17 days after exposure; most symptoms will go away within a month, but if it spreads from a person’s lungs, the illness can become severe and require months of treatment.
People can be exposed to histo and other fungal pathogens through activities that disrupt soil, like farming, landscaping, and construction. They can also be exposed inside caves and while working in basements and attics. Spec noted: “It’s important for the medical community to realize these fungi are essentially everywhere these days and that we need to take them seriously and include them in considering diagnoses.”
‘Zombie ant’ fungi infected with parasites of their own
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Around the world, a parasitic fungus transforms ants into “zombies.”
The fungus is like something out of a horror movie: The organism hijacks the body and brain of its ant host, mind-controlling it into abandoning its nest and climbing a nearby tree.
There, the infected ant clamps its jaws around a leaf, dangling above the forest floor, and dies in a matter of days as the fungus digests it. Bursting through its host’s body, the fungus then sends down a shower of spores to infect the next generation of ant prey.
Scientifically categorized in the genus Ophiocordyceps, the more than two dozen species of zombie ant fungus populate the globe, including Florida, Brazil and Japan; scientists suspect that each of the dozens of ant species affected has its own specialized Ophiocordyceps strain.
So far, scientists have figured out the molecular mechanism of the parasitic interaction between fungus and ant that forms the basis of the behavioral manipulation, according to a 2020 study. How exactly these parasites systematically operate, however, is poorly understood.
Now, scientists have revealed that the ant-attacking fungus is infected with fungal parasites of its own, which could be helping to keep ant zombification in check, according to a new study.
Dr. João Araújo, an assistant curator of mycology at the New York Botanical Garden, has been trekking through tropical forests in search of zombie ants for more than a decade. Over the years, he kept noticing something strange: a fuzzy white fungus growing on top of the zombie ant fungus.
Other scientists have noted the mystery fungus for decades, but Araújo and his colleagues decided to become the first scientists to systematically dig into the matter, zeroing in on a strain of zombie ants from Florida. The researchers described the physical structure of the fungi growing on top of the zombie ant fungus and sequenced their DNA in a study published November 9 in the journal Persoonia.
In doing so, the team discovered two new genera of fungus previously unknown to science.
“We realized that there were two different lineages of fungi, novel lineages of fungi, infecting one species of zombie ant fungus in Florida,” said Araújo, the study’s lead author.
Each of the two newly discovered fungi belongs to its own genus. One of the new fungi, Niveomyces coronatus, is responsible for the fuzzy white coating on the zombie ant fungus — a component of its name (“niveo”) comes from the Latin for “snowy.” The second new fungus, Torrubiellomyces zombiae, is harder to spot: The little black blobs “look like fleas,” according to Araújo.
The fungi attacking the zombie ant fungus don’t, in turn, zombify their host, but they do feed on its tissues and appear to cause it harm. “Every time we see these new genera we described growing on the fungus, the fungus looks pretty beaten up, really consumed by this other fungus,” Araújo said.
“In some cases, it castrates Ophiocordyceps (the zombie-making fungus) first, so it cannot shoot the spores anymore, and then it grows and then consumes the whole fungus.” Since Niveomyces and Torrubiellomyces are so new to science, it’s not yet clear how much of an effect they have on zombie ant fungi populations overall.
These new genera are the first parasites officially described as infecting the zombie ant fungus, but the researchers suspect there could be others out there. “I think it’s more common than we think. Parasitism is a super lucrative sort of lifestyle,” said senior study author Dr. Charissa de Bekker, an assistant professor at Utrecht University in the Netherlands. “It might be the most dominant lifestyle on the planet.”
What’s more, she said, parasites in general and parasitic fungi in particular are poorly studied. “The fact that we had to invoke two new genera tells you how little we know about this part of the fungal tree of life,” de Bekker said.
By deepening our understanding of the zombie ant fungus, the new research could have applications that go beyond the study of fungi, said Dr. Carolyn Elya, a postdoctoral fellow in organismic and evolutionary biology at Harvard University. She was not involved with the study.
“Ophiocordyceps has basically over evolutionary time become an expert neuroscientist. It knows exactly what buttons to push and how to get the ant to do what it wants,” she said. “By studying how it’s figured out how to solve this problem, we can have insight into our more general goal of trying to understand how brains work or produce behavior.”
Uh Oh, Scientists Figured Out How to Grow Terrifying Parasitic Mushrooms in the Lab
Just in time for Halloween, scientists in Korea say they’ve found a better way to grow an insect-destroying mushroom in the lab. Their work could make studying these fungi easier, which is important, since they and the chemicals they produce may actually have medicinal uses for humans, creepy as they are.
The fungi is known as Cordyceps. Members of this genus, along with a related but distinct genus called Ophiocordyceps, are parasitic, usually feeding on insects and other arthropods. These fungi will invade and often kill their hosts, though not before using them as fuel to grow their fruiting bodies (technically, this is the part of the fungi that we call the mushroom) and release new infectious spores into the world to start the process all over again. Some members of Ophiocordyceps are also known for “zombifying” their ant hosts by manipulating their behavior before death to ensure their optimal survival.
As horrifying as their way of life is, some members of Cordyceps are considered food in parts of Asia. They’ve also been used in traditional Chinese medicine and more recently are being sold as supplements (supplements of any kind, it should be noted, have little quality control and aren’t necessarily harmless). And early research has suggested that Cordyceps produce chemicals that could have beneficial health effects, particularly a compound called cordycepin. Some studies have indicated, for instance, that cordycepin might have anti-viral or cancer-fighting properties.
This research has largely come from animal or lab studies, though, meaning it will take a lot more evidence in humans to confirm any potential benefits. These experiments and any eventual widespread use of Cordyceps will also require having ample supplies of the fungi or their compounds, and that’s a challenge. Though these fungi are found throughout the world, they’re hard to find and harvest from the wild. There are now ways to cultivate them in the lab, but the current methods only yield low amounts of healthy Cordyceps or cordycepin, making them hard to scale up.
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Researchers at Chungbuk National University tried to improve on these methods, which usually use brown rice as the growth medium. They theorized that these mushrooms would grow better on richer sources of protein—namely, insects. They also guessed that their diet would affect how large the fungi grew and how much cordycepin they produced, so they tested out different types of insects. These insect nurseries were kept growing for two months before the researchers harvested the Cordyceps. The team’s findings, published Wednesday in Frontiers in Microbiology, suggests that their insect theory was right on the money.
“Cordyceps grown on edible insects contained approximately 100 times more cordycepin compared to Cordyceps on brown rice,” said study author Mi Kyeong Lee, a professor at Chungbuk, in a statement from Frontiers.
As expected, though, there were differences in how the insect food affected their growth. The fungi were most plentiful when they fed on mealworms and silkworm pupae, for instance. But they actually produced the most cordycepin when they fed on Japanese rhinoceros beetles. The team’s work also indicates that it was the fat content of the insects, not their protein, that predicted how much cordycepin the mushrooms produced. The rhinoceros beetles were especially full of a type of fat called oleic acid, and once the team introduced oleic acid to a low-fat insect feed, the Cordyceps’ production of cordycepin rose as well.
“The cultivation method of Cordyceps suggested in this study will enable the production of cordycepin more effectively and economically,” Lee said.
While these scientists may have found an improved method of growing Cordyceps in the lab, you probably shouldn’t expect mass production just yet. The authors note that churning out insects on an industrial scale isn’t easy, either. So if these freaky fungi do turn out to be medically valuable, there’ll be more challenges ahead in developing them for mass use. That said, there is at least one research team at Oxford University actively studying a modified version of cordycepin as a cancer drug in early human trials.
Traces of Fungi Found Growing Inside Tumors Could Be Linked With Patient Outcomes : ScienceAlert
Scientists discovered traces of fungi lurking in the tumors of people with different types of cancer, including breast, colon, pancreatic, and lung cancers.
However, it’s still not clear that these fungi play any role in the development or progression of cancer.
Two new studies, both published Sept. 29 in the journal Cell, uncovered DNA from fungal cells hiding out in tumors throughout the body.
In one study, researchers dusted for the genetic fingerprints of fungi in 35 different cancer types by examining more than 17,000 tissue, blood, and plasma samples from cancer patients.
Not every single tumor tissue sample tested positive for fungus, but overall, the team did find fungi in all 35 cancer types assessed.
“Some tumors had no fungi at all, and some had a huge amount of fungi,” co-senior author Ravid Straussman, a cancer biologist at the Weizmann Institute of Science in Rehovot, Israel, told STAT; often, though, when tumors contained fungi they did so in “low abundances,” the team noted in their report.
Based on the amount of fungal DNA his team uncovered, Straussman estimated that some tumors contain one fungal cell for every 1,000 to 10,000 cancer cells.
If you consider that a small tumor can be laden with a billion or so cancer cells, you can imagine that fungi may “have a big effect on cancer biology,” he said.
Related: Dormant cancer cells may ‘reawaken’ due to change in this key protein
Straussman and his team found that each cancer type tended to be associated with its own unique collection of fungal species; these included typically harmless fungi known to live in humans and some that can cause diseases, like yeast infections.
In turn, these fungal species often coexisted with particular bacteria within the tumor. For now, it’s unknown if and how these microbes interact in the tumor and if their interactions help fuel the cancers’ spread.
The second Cell study uncovered similar results to the first but focused specifically on gastrointestinal, lung, and breast tumors, Nature reported. The researchers found that each of those three cancer types tended to host the fungal genuses Candida, Blastomyces, and Malassezia, respectively.
Both research groups found hints that the growth of certain fungi may be linked to worse cancer outcomes. For example, Straussman’s group found that breast cancer patients with the fungus Malassezia globosa in their tumors showed worse survival rates than patients whose tumors lacked the fungus.
The second group, led by immunologist Iliyan Iliev at Weill Cornell Medicine in New York City, found that patients with a relatively high abundance of Candida in their gastrointestinal tumors showed increased gene activity linked to rampant inflammation, cancer spread, and poor survival rates, Nature reported.
Despite these early hints, neither study can definitively say if fungi actually drive these poor outcomes or if aggressive cancers just create an environment where these fungi can easily grow.
The studies also don’t address if fungi can contribute to cancer development, pushing healthy cells to turn cancerous.
Both studies come with similar limitations. For example, both pulled tissue and blood samples from existing databases, and it’s possible that some samples may have been contaminated with fungi during the collection process, Ami Bhatt, a microbiome specialist at Stanford University in California, told Nature.
Both research groups attempted to weed out such contaminants, but even with these precautions, Bhatt said that it would be best if the results could be replicated with samples taken in a sterile environment.
Straussman told STAT that these initial studies serve as a springboard for future research into mycobiota, meaning the communities of microbes associated with cancers.
“As a field, we need to evaluate everything we know about cancer,” he said. “Look at everything through the lens of the microbiome – the bacteria, the fungi, the tumors, even viruses. There are all these creatures in the tumor, and they must have some effect.”
Related content:
This article was originally published by Live Science. Read the original article here.
Fungi grow inside cancerous tumors, scientists discover
Scientists discovered traces of fungi lurking in the tumors of people with different types of cancer, including breast, colon, pancreatic and lung cancers. However, it’s still not clear that theise fungi plays any role in the development or progression of cancer.
Two new studies, both published Sept. 29 in the journal Cell, uncovered DNA from fungal cells hiding out in tumors throughout the body. In one study (opens in new tab), researchers dusted for the genetic fingerprints of fungi in 35 different cancer types by examining more than 17,000 tissue, blood and plasma samples from cancer patients. Not every single tumor tissue sample tested positive for fungus, but overall, the team did find fungi in all 35 cancer types assessed.
“Some tumors had no fungi at all, and some had a huge amount of fungi,” co-senior author Ravid Straussman, a cancer biologist at the Weizmann Institute of Science in Rehovot, Israel, told STAT (opens in new tab); often, though, when tumors contained fungi they did so in “low abundances,” the team noted in their report.
Based on the amount of fungal DNA his team uncovered, Straussman estimated that some tumors contain one fungal cell for every 1,000 to 10,000 cancer cells. If you consider that a small tumor can be laden with a billion or so cancer cells, you can imagine that fungi may “have a big effect on cancer biology,” he said.
Related: Dormant cancer cells may ‘reawaken’ due to change in this key protein
Straussman and his team found that each cancer type tended to be associated with its own unique collection of fungal species; these included typically harmless fungi known to live in humans and some that can cause diseases, like yeast infections. In turn, these fungal species often coexisted with particular bacteria within the tumor. For now, it’s unknown if and how these microbes interact in the tumor and if their interactions help fuel the cancers’ spread.
The second Cell study (opens in new tab) uncovered similar results to the first but focused specifically on gastrointestinal, lung and breast tumors, Nature reported (opens in new tab). The researchers found that each of those three cancer types tended to host the fungal genuses Candida, Blastomyces and Malassezia, respectively.
Both research groups found hints that the growth of certain fungi may be linked to worse cancer outcomes. For example, Straussman’s group found that breast cancer patients with the fungus Malassezia globosa in their tumors showed worse survival rates than patients whose tumors lacked the fungus. The second group, led by immunologist Iliyan Iliev at Weill Cornell Medicine in New York City, found that patients with a relatively high abundance of Candida in their gastrointestinal tumors showed increased gene activity linked to rampant inflammation, cancer spread and poor survival rates, Nature reported.
Despite these early hints, neither study can definitively say if fungi actually drive these poor outcomes or if aggressive cancers just create an environment where these fungi can easily grow. The studies also don’t address if fungi can contribute to cancer development, pushing healthy cells to turn cancerous,
Both studies come with similar limitations. For example, both pulled tissue and blood samples from existing databases, and it’s possible that some samples may have been contaminated with fungi during the collection process, Ami Bhatt, a microbiome specialist at Stanford University in California, told Nature. Both research groups attempted to weed out such contaminants, but even with these precautions, Bhatt said that it would be best if the results could be replicated with samples taken in a sterile environment.
Straussman told STAT that these initial studies serve as a springboard for future research into mycobiota, meaning the communities of microbes associated with cancers. “As a field, we need to evaluate everything we know about cancer,” he said. “Look at everything through the lens of the microbiome — the bacteria, the fungi, the tumors, even viruses. There are all these creatures in the tumor, and they must have some effect.”
Are long nails health hazards? Experts weigh in on bacteria, fungi
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Fix annoying wardrobe fails with nail polish.
ProblemSolved, USA TODAY
Long nails are a major trend these days, seen on the hands of superstars like Cardi B and Billie Eilish. But a biologist warns this new trend may come with health hazards when considering what may be growing underneath.
Jeffrey Kaplan, a biology professor at American University, told USA TODAY that the area under the fingernail in the crevice is where most of the bacteria live.
“The longer the nail, the more surface area there is for microorganisms to adhere,” he said. “Studies have found 32 different bacteria and 28 different fungi underneath fingernails.”
Kaplan said it doesn’t matter if you have long artificial nails, long natural nails, gel nails, acrylic nails or nail polish, because there is an increased probability of carrying microorganisms which makes it more difficult to decontaminate with handwashing or scrubbing.
Studies find MRSA, staph underneath
One study found MRSA, an antibiotic-resistant bacteria that causes serious infections in hospitalized patients, underneath half of the fingernail samples collected, according to Kaplan.
Also, some of the bacteria under nails can be found on the skin like staphylococcus which can lead to an infection.
“You can transmit fingernail bacteria to your system by scratching, nail-biting, nose-picking and finger-sucking,” Kaplan said.
He said the worst thing that could happen from the bacteria and fungi is a nail infection, which would not be life-threatening, but could leave your fingernails disfigured.
Infant deaths linked to long fingernails
That is why most, if not all healthcare workers, are required to wear short nails due to being at risk for transmitting disease, according to Kaplan..
Two nurses at an Oklahoma City hospital may have contributed to the deaths of 16 babies in 1997 and 1998 because of bacteria found underneath their long nails, The New York Times reported.
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Epidemiologists found a link between the deaths of the infants in the neonatal unit and the bacteria under the nails but did not prove it was the definite cause.
“When surgeons scrub for surgery and then they test their hands, there’s always bacteria under the fingernail and you can’t get rid of it,” Kaplan said.
Long nails trend on social media
Kayla Newman, a nail tech based in North Carolina, told USA TODAY that none of her clientele has had infections or “nasty nails” in her eight years of service.
“Generally people who have long nails know how to maneuver with them and keep them clean,” she said. “If you’re spending upwards of $60 to get your nails done and you don’t keep them clean, that doesn’t make sense.”
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Newman has seen the trend for long nails grow over the last couple of years, and social media platforms like Instagram and TikTok showcase artistic designs on nails that can be over 2 inches long.
She said the most common complaint she gets from clients who have long nails are broken nails, especially if they are new to the trend.
Newman suggests for people with long nails to regularly make appointments with their nail tech because the strength of nails can shift when they grow out.
“Nails are an awesome luxury to have,” she said. “I encourage people to get them done because when you look at your hands and see them nice and done whether they are long or short, it makes you feel amazing.”
Follow reporter Asha Gilbert @Coastalasha. Email: agilbert@usatoday.com.
A Toxic Fungus Could Be Contributing to Some People’s Irritable Bowel Disease
Some strains of yeast in the human gut can produce toxins that could contribute to irritable bowel disease (IBD), according to new research.
These “high-damaging” Candida albicans yeast strains aren’t usually a problem when they are kept in balance, but in the guts of those with IBD, the fungi appear to proliferate, triggering inflammation.
The research was focused on a form of IBD known as ulcerative colitis (UC), which is marked by inflammation and frequent ulceration of the lining in the large intestine. In this part of the gut, fungi are also highly abundant and rich in diversity.
When scientists compared the colons of 40 UC patients against 38 controls who didn’t have IBD, they found C. albicans strains were over-represented in the guts of those with UC.
The more severe the case, the more likely the patient was to show a higher abundance of Candida in their colon.
To test how these strains impact inflammation, researchers turned to mouse models. In mice without colon inflammation, the yeast strains identified in humans did not proliferate. But in mice with colon inflammation, mimicking UC, the yeast did.
Looking closer, researchers realized some yeast strains were producing a potent toxin called candidalysin, which can damage immune cells, triggering further inflammation.
Even when the sickest mice were given steroids, a common prescription for UC, the “high-damaging” strains of gut fungi continued secreting toxins, which could explain why current IBD treatments often fail to resolve symptoms.
“Our findings suggest that C. albicans strains do not cause spontaneous intestinal inflammation in a host with intact immunity,” says Iliyan Iliev from Weill Cornell Medicine at Cornell University in the US.
“But they do expand in the intestines when inflammation is present and can be a factor that influences response to therapy in our models and perhaps in patients.”
In other words, for most people, C. albicans strains are not a problem. Even the ones that produce cell-damaging toxins can also help the immune system. In the gut of someone with UC, however, where inflammation is widespread, some of these yeast strains seem to take off, causing more harm than good.
However, it’s still up for debate which comes first, the toxins or the inflammation.
“We do not know whether specific strains are acquired by specific patients during the course of disease or whether they have been always there and become a problem during episodes of active disease,” says Iliev.
“Nevertheless, our findings highlight a mechanism by which commensal [that is, internal cohabitants] fungal strains can turn against their host and overdrive inflammation.”
In the lab, scientists found the candidalysin toxin produced via yeast can damage specific immune cells, known as macrophages. In turn, this can trigger a storm of cytokines, which are proteins that promote inflammation via the immune system.
In mice, toxin-producing yeast induced an expansion of T-cells and white blood cells called neutrophils, which can both drive inflammation and lead to tissue damage.
Neutrophils are often more abundant in those with active IBD, and the new results suggest their presence could be tied to a rise in fungal toxins. When researchers blocked the cytokine signaling pathway that kicks neutrophils into action in mouse models, it reduced overall colon inflammation.
This signaling pathway could thus provide drug makers a target for future IBD treatments. Direct antifungal therapies could also prove useful.
Compared to the microbiota, which is the gut’s community of microbes, there is very little research out there on the fungi in our intestines, known as the mycobiota.
In fact, between 2008 and 2018, there were almost a hundred times more peer-reviewed publications on the microbiota than the mycobiota.
Recent research suggests that is an oversight. Bacteria and fungi in the gut have similar effects on the immune system, as well as nutrition; they can interact, too. Some forms of bacteria, for instance, appear to keep C. albicans in check.
While past studies have drawn a connection between the mycobiota and IBD, this is one of the first studies to dig into the mechanism behind this relationship.
The authors are now working on several follow-up studies to see how toxin-producing yeast inflames the colon and to figure out which patients will respond best to antifungal treatments.
The study was published in Nature.