Spacebound Bacteria Inspire Earthbound Remedies
WASHINGTON -- Recent research aboard the space shuttle is giving scientists a better understanding of how infectious disease occurs in space and could someday improve astronaut health and provide novel treatments for people on Earth."With our space-based research efforts, including the International Space Station, we are not only continuing our human presence in space, but we are engaged in science that can make a real difference in people's lives here on Earth," said NASA Administrator Charles Bolden. "NASA's leadership in human spaceflight allows us to conduct innovative and ground-breaking science that reveals the unknown and unlocks the mysteries of how disease-causing agents work."
The research involves an opportunistic pathogen known as Pseudomonas
aeruginosa, the same bacterium that caused astronaut Fred Haise to
become sick during the Apollo 13 mission to the moon in 1970.
Scientists studying the bacterium aboard the shuttle hope to unlock
the mysteries of how disease-causing agents work. They believe the
research can lead to advanced vaccines and therapies to better fight
infections. The findings are based on flight experiments with
microbial pathogens on NASA shuttle missions to the International
Space Station and appear in a recent edition of the journal Applied
and Environmental Microbiology.
"For the first time, we're able to see that two very different species
of bacteria - Salmonella and Pseudomonas - share the same basic
regulating mechanism, or master control switch, that micro-manages
many of the microbes' responses to the spaceflight environment," said
Cheryl Nickerson, associate professor at the Center for Infectious
Diseases and Vaccinology, the Biodesign Institute at Arizona State
University (ASU) in Tempe. "We have shown that spaceflight affects
common regulators in both bacteria that invariably cause disease in
healthy individuals [Salmonella] and those that cause disease only in
people with compromised immune systems [Pseudomonas]."
By studying the global gene expression patterns in bacterial pathogens
like Pseudomonas and Salmonella, Nickerson's team learned more about
how they react to reduced gravity.
Pseudomonas aeruginosa can coexist as a benign microbe in healthy
individuals, but poses a serious threat to people with compromised
immune systems. It is the leading cause of death for those suffering
from cystic fibrosis and is a serious risk to burn victims. However,
a high enough dosage of Salmonella typhimurium always will cause
disease, even in healthy individuals.
During the initial study in 2006, two bacterial pathogens, Salmonella
typhimurium and Pseudomonas aeruginosa, and one fungal pathogen,
Candida albicans, were launched to the station aboard shuttles. They
were allowed to grow in appropriately contained vessels for several
days. Nickerson's team was the first to evaluate global gene and
protein expression (how the bacteria react at the molecular level)
and virulence changes in microbes in response to reduced gravity.
"We discovered that aspects of the environment that microbes
encountered during spaceflight appeared to mimic key conditions that
pathogens normally encounter in our bodies during the natural course
of infection, particularly in the respiratory system,
gastrointestinal system and urogenital tract," Nickerson said. NASA's
Advanced Capabilities Division Director, Benjamin Neumann added that,
"This means that in addition to safeguarding future space travelers,
such research may aid the quest for better therapeutics against
pathogens here on Earth."
The initial study and follow-on space experiments show that
spaceflight creates a low fluid shear environment, where liquids
exert little force as they flow over the surface of cells. The low
fluid shear environment of spaceflight affects the molecular genetic
regulators that can make microbes more infectious. These same
regulators might function in a similar way to regulate microbial
virulence during the course of infection in the human body.
"We have now shown that spaceflight conditions modified molecular
pathways that are known to be involved in the virulence of
Pseudomonas aeruginosa," said Aurelie Crabbe, a researcher in Dr.
Nickerson's lab at ASU and the lead author of the paper. "Future work
will establish whether Pseudomonas also exhibits increased virulence
following spaceflight as did Salmonella."
NASA's Fundamental Space Biology Program sponsored and funded the
research conducted by Crabbe and Nickerson along with their
colleagues at the Biodesign Institute at ASU. They collaborated with
the University of Colorado School of Medicine, University of Arizona,
Belgian Nuclear Research Center, Villanova University, Tulane
University, Affymetrix Inc, and NASA scientists.
For an abstract of the journal article on this research, visit:
http://www.ncbi.nlm.nih.gov/
For more information about NASA programs, visit:
http://www.nasa.gov
Source: NASA
