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fungus

LabTV: Curious About the Microbiome

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Keisha FindleyWhen people think about the human microbiome—the scientific term for all of the microbes that live in and on our bodies—the focus is often on bacteria. But Keisha Findley, the young researcher featured in today’s LabTV video, is fascinated by a different part of the microbiome: fungi.

While earning her Ph.D. at Duke University, Durham, N.C., Findley zeroed in on Cryptococcus neoformans, a common, single-celled fungus that can lead to life-threatening infections, especially in people with weakened immune systems. Now, as a postdoctoral fellow at NIH’s National Human Genome Research Institute, Bethesda, MD, she is part of an effort to survey all of the fungi, as well as bacteria, that live on healthy human skin. The goal is to get a baseline understanding of these microbial communities and then examine how they differ between healthy people and those with skin conditions such as acne, athlete’s foot, skin ulcers, psoriasis, or eczema.


Snapshots of Life: Host vs. Pathogen

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Cryptoccocus neoformans

Caption: This scanning electron microscopy image shows mouse macrophages (green) interacting with a fungal cell (blue).
Credit: Sabriya Stukes and Hillary Guzik, Albert Einstein College of Medicine

Macrophages are white blood cells that generally destroy foreign invaders by engulfing them. It’s a tried-and-true strategy, but it doesn’t always work. Cryptoccocus neoformans, a deadly fungal pathogen commonly found in the feces of pigeons, can foil even the best macrophages. No one has captured this grand escape—but researchers are getting a whole lot closer to doing so.

Sabriya Stukes, an NIH-funded microbiologist at New York’s Albert Einstein College of Medicine, studies the interactions between C. neoformans and macrophages to determine how the former causes the lung infection cryptococcosis, which can be deadly for people with compromised immune systems. Stukes believes what makes C. neoformans so dangerous is that it can survive the acid death chamber inside macrophages—a situation that spells doom for most other pathogens. A big reason behind this fungus’s power of survival is its thick coat of polysaccharides, which serves as woolly-looking armor. Once a macrophage engulfs the fungus, this coat can give the white blood cell “indigestion,” prompting it to spit the fungus back into the lungs where it can cause disease. 


Yes, It’s True: There’s Fungus Among Us

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A fluorescent pink blob with a blue-green shaft surrounded by purple and blue dots

Caption: A fluorescent microscope image of a human hair shaft in the skin surrounded by bacteria (purple) and fungi (blue).
Credit: Alex Valm, National Human Genome Research Institute, NIH.

Athlete’s foot, ringworm, diaper rash, dandruff, some cases of sinusitis, and vaginal yeast infections are all caused by fungi. These microscopic co-travelers live in the air, water, soil, and, so it happens, on our body. NIH researchers have just completed the first census of the fungi that live on the human body, and it’s quite a diverse collection [1].

The researchers used Q-tips and toenail clippings to sample 14 sites from 10 healthy human volunteers and then analyzed the DNA to determine the identity of the fungi in these locations. They focused on sites—like the back of the head, nostril, feet, and groin, for example—that are frequently plagued with diseases thought to be caused by fungi. (The same team of researchers took a similar approach a few years back to catalog all the bacteria that live on human skin [2].)