Task Apoptosis and Immune Homeostasis During Hindlimb Unloading (Completed)
Last Published:  11/23/20 11:55:12 AM (Central)
Short Title: Immune Homeostasis
Responsible HRP Element: Human Health Countermeasures
Collaborating Org(s):
National Space Biomedical Research Institute (NSBRI)
Funding Status: Completed - Task completed and produced a deliverable
Procurement Mechanism(s):
Space flight causes lymphopenia, abnormally low mitogen responses, and reduced production of antibodies and cytokines.  Space flight-associated factors such as microgravity, lack of load bearing, stress, and radiation are believed to contribute to these effects, but the exact mechanisms are unknown.  Ground-based mouse models such as hind limb unloading (HU) and irradiation cause similar effects.  We hypothesize that these changes result from lymphocyte apoptosis induced by the cell surface receptor, Fas, in a manner dependent on endogenous opioids.  Furthermore, we predict that radiation exposure and HU act synergistically. 

The overall goal is to determine the mechanisms underlying apoptosis-related immune modulation using ground-based models.
  1. Elucidate the role of Fas and endogenous opioids in the modulation of the immune system by HU and radiation.
  2. Determine the effect of HU and radiation on lymphocyte dynamics and immune responses. 
  3. In addition, because autoimmune disease is often associated with stress and radiation exposure, we will determine whether HU and radiation promote autoimmunity. 

Integration/Unique Aspects: TBD

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