San Francisco VA Medical Center researchers say they’ve identified a set of key immune-response genes that do not turn on in a weightless environment.

The scientists said their discovery is another clue in the effort to solve a nearly 40-year-old mystery of why the human immune system does not function well in the weightlessness of space.



The researchers — led by biochemist and former astronaut Millie Hughes-Fulford — identified a signaling pathway called PKA that in a gravity field responds to a pathogen by stimulating the expression of 99 genes, that in turn cause the activation of T-cells, which are essential for proper immune function.



Hughes-Fulford found in the simulated absence of gravity, the PKA pathway did not respond to the pathogen’s presence. As a result, activation of T-cells was severely reduced.



A Russian spacecraft will carry the same experiment into space next year.



We know how these genes behave in simulated microgravity, she said. The results from Soyuz should tell us what happens during spaceflight, in real microgravity.



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