Differential effects of hypergravity on immune dysfunctions induced by simulated microgravity

Area of Science:

• Space biology
• Immunology
• Gravitational biology

Background:

• Spaceflight microgravity (μg) causes immune dysregulation, increasing monocyte inflammation and reducing T cell activation.
• Hypergravity, or artificial gravity, shows promise for mitigating deconditioning and has therapeutic potential on Earth.
• The effects of hypergravity on immune cells, particularly in counteracting microgravity-induced changes, remain under-explored.

Purpose of the Study:

• To investigate if mild hypergravity (2.8g) can prevent or treat immune dysregulations caused by simulated microgravity (s-μg).
• To analyze T cell and monocyte activation states and cytokine patterns under different gravitational conditions and countermeasure timings.

Main Methods:

• Whole blood samples were incubated with antigen under simulated microgravity (fast clinorotation) or hypergravity (2.8g).
• Hypergravity countermeasures were applied in three sequences: preconditioning (before s-μg), intermediate (during s-μg), and post-treatment (after s-μg).
• Monocyte and T cell activation markers (e.g., CD69) and cytokine secretion (e.g., IFNγ) were analyzed.

Main Results:

• Simulated microgravity enhanced monocyte pro-inflammatory states and reduced T cell activation.
• Hypergravity alone reduced monocyte pro-inflammatory states compared to 1g controls.
• Hypergravity countermeasures did not resolve monocyte inflammation.
• T cell preconditioning with 2.8g before s-μg restored antigen-induced CD69 expression and IFNγ secretion to control levels and beyond.

Conclusions:

• Mild hypergravity (2.8g) can serve as a gravitational preconditioning strategy to prevent adaptive immune cell dysfunction induced by microgravity.
• Hypergravity may enhance immune cell function, acting as a potential booster for T cell responses.
• This study provides a proof-of-concept for using hypergravity as a countermeasure in spaceflight settings.