Plague alters cell death to kill host

PUBLIC RELEASE DATE:

14-Apr-2014

Contact: Marla Paul marla-paul@northwestern.edu 312-503-8928 Northwestern University

Northwestern Medicine scientists are continuing to unravel the molecular changes that underlie one of the world's deadliest and most infamous respiratory infections.

When the bacterium Yersinia pestis enters the lungs, it causes pneumonic plague, a disease that is 100 percent fatal if untreated. The way in which Y. pestis evades the immune system and kills people in a matter of days has largely confounded scientists, until now.

Following a 2007 study demonstrating that the presence of a protein called the plasminogen activator protease (Pla) is required for Y. pestis to live inside the lungs, Wyndham Lathem, PhD, assistant professor in Microbiology-Immunology, has found what role Pla plays during disease.

The activator shuts down a molecule, Fas ligand (FasL), which stimulates a form of programmed cell death known as apoptosis. The result is a disrupted immune response during infection. This allows Y. pestis to overwhelm the lungs, causing death.

"This is the first time anyone has shown how bacteria can subvert apoptotic cell death by directly destroying Fas ligand," said Lathem, a member of the Center for Genetic Medicine and Interdepartmental Immunobiology Center.

The findings were published April 9 in Cell Host & Microbe.

To study its effects, scientists added Pla to glass slides with various fluorescently-tagged proteins. If the protease showed an affinity for a specific protein, it would chew off pieces, making it appear less florescent when viewed under a microscope.

Originally posted here:
Plague alters cell death to kill host