Studying the effects of space travel from the left are Wyle Life Sciences’ Mayra Nelman-Gonzalez, NASA’s Brian Crucian, Ph.D., UTHealth’s Jeffrey Actor, Ph.D., and UTHealth’s Shen-An Hwang, Ph.D.
Studying the effects of space travel from the left are Wyle Life Sciences’ Mayra Nelman-Gonzalez, NASA’s Brian Crucian, Ph.D., UTHealth’s Jeffrey Actor, Ph.D., and UTHealth’s Shen-An Hwang, Ph.D.

A space test conducted by researchers at McGovern Medical School and NASA helps explain why some astronauts may have increased risk of infections following missions.

When the Space Shuttle Atlantis returned from its 13-day mission on July 21, 2011, scientists analyzed the immune systems of mice aboard for experimental purposes and found changes that could impair the detection of disease-causing agents. Findings appear in PLOS One.

The investigators also analyzed blood samples taken from astronauts aboard the orbiter and discovered similar changes in the responsiveness of immune cells triggered by receptors on cell surfaces.

“With deep space missions planned to Mars that could take months, factors contributing to reoccurring and opportunistic infections need to be identified and remedied,” said Dr. Jeffrey Actor, the study’s senior author and a professor of pathology and laboratory medicine.

These changes could compromise the ability of immune system phagocytic cells to track down bacteria and other disease-causing pathogens. “The information uncovered could allow for the design of therapeutic treatments to recover immune function quicker post-flight,” Actor said

Actor, who is also on the faculty of The University of Texas Graduate School of Biomedical Sciences at Houston, said, “Cells involved in immune surveillance use receptors on their cell surface to recognize and respond to microorganisms. Our research suggests that there may be changes to these receptors after a period of weightlessness.”

The study focused on white blood cells taken from the spleens (splenocytes) of mice. The scientists were looking for changes to T cells and dendritic cells, which play critical roles in the immune response to pathogens.

Distinct changes were found when the splenocytes of the mice on the mission were compared to earthbound mice, Actor said. There was a drop in the intensity of the markers that cells use to respond to their targets.

“Data from this study shed additional light toward molecular mechanisms involved in immune changes induced by spaceflight that could alter activation of innate and adaptive immunity, at least post flight,” the authors wrote in the paper.

Actor’s co-authors include Dr. Shen-An Hwang, assistant professor of pathology and laboratory medicine at UTHealth; Dr. Brian Crucian, immunologist at NASA’s Johnson Space Center; and Dr. Clarence Sams, clinical immunologist and biochemist at the Johnson Space Center.

The study is titled “Post-Spaceflight (STS-135) Mouse Splenocytes Demonstrate Altered Activation Properties and Surface Molecule Expression.”

-Rob Cahill, Office of Public Affairs