Study Identifies Immune Cell Alterations in Microgravity

In a study published in Nature Communications, scientists from the Buck Institute and Weill Cornell Medical College have unveiled the intricate ways in which microgravity conditions affect the cells of the immune system. The team not only mapped the cellular changes induced by simulated microgravity it also identified potential "space nutraceuticals" to counter these aberrant effects.

"We show how simulated microgravity shapes immune cells and how the changes in force alter the cells' function at the single-cell level," said co-senior author Daniel Winer. "This level of resolution is new and exciting in understanding the effects of microgravity on cells."

By combining data from simulated microgravity experiments, spaceflight studies involving astronauts and mice on the International Space Station, the researchers created a comprehensive picture of how reduced gravity impacts various immune cells, including lymphocytes and monocytes, which are crucial players in immunity. 

The study not only has implications for understanding immune aging on Earth, as the observed changes resemble those seen during normal aging, but also paves the way for developing countermeasures to maintain normal immunity under harsh conditions like spaceflight.

"Our work provides a resource to better understand how and why the immune system changes in simulated microgravity and spaceflight," said co-senior author David Furman. "We also provide a way to develop countermeasures to maintain normal immunity under these harsh conditions."

Astronauts in low earth orbit, such as on the International Space Station, suffer from immune system problems, especially infections, latent viruses reactivating, and skin sensitivity. These reactions occur even on short-term spaceflights. Previous studies using actual or simulated microgravity conditions have found impaired function of various immune cells. However, the fundamental mechanisms, genes, and pathways that explain immune dysfunction in microgravity were mostly unclear, the researchers said.

The team examined in depth how 25 hours of simulated microgravity affects the human peripheral blood mononuclear immune system, using samples from 27 healthy human donors between the ages of 20 and 46. To simulate an environment with almost no gravity, the team grew the cells inside of a Rotating Wall Vessel, a device developed by NASA to simulate microgravity conditions. To explore the changes caused by reduced gravity, the team used a number of techniques, including sequencing and super-resolution microscopy. They then validated their findings by comparing their data with other space studies done in humans and mice.

After uncovering several genes and biochemical pathways affected by microgravity, the team used machine learning technology developed by Furman to identify potential compounds that could protect immune cells. One promising candidate, the plant pigment quercetin, was found to reverse approximately 70 percent of the changes caused by lack of gravity and protect cells from excessive reactive oxygen species.

"These findings define hallmarks of immune cell alteration in simulated microgravity, with correlation to spaceflight exposures in mice and humans," said Winer. "This work helps define avenues for future research in mechanoimmunology and astroimmunology and provides opportunities to develop countermeasures to maintain normal cellular function in space."