Snapshots of Life: Host vs. Pathogen

Posted on July 9, 2015 by Dr. Francis Collins

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.

Stukes wants to know how exactly C. neoformans triggers this escape. To capture the event as it unfolds, Stukes has joined forces with microscopist Hillary Guzik. After infecting macrophages withC. neoformans, Stukes uses a scanning electron microscope to capture the interactions between the mouse macrophages (green) and pathogenic fungal cell (blue). She sends the images to Guzik, who colorizes and turns them into works of art; she even makes the cellular detritus (pink) look good!

In this particular image, one of the winners of the Federation of American Societies for Experimental Biology’s 2014 BioArt competition, a single C. neoformans is ensnared in the tentacles of two macrophages. By imaging these host-pathogen interactions at various stages, Stukes wants to record the precise moment when a macrophage expels the fungal cell. She hopes that by capturing it all under the microscope, we can improve our understanding of how this common environmental pathogen manipulates the immune system to cause disease.

Links:

BioArt (Federation of American Societies for Experimental Biology)

Cryptococcosis (Medline Plus Medical Encyclopedia)

Casadevall Laboratory (Albert Einstein College of Medicine, New York)

NIH support: National Institute of Allergy and Infectious Diseases