Low-dose γ-rays modify CD4(+) T cell signalling response to simulated solar particle event protons in a mouse model

Area of Science:

• Space science and radiation biology
• Immunology and cell signaling

Background:

• Astronauts face risks from low-dose/low-dose-rate (LDR) radiation and high-dose solar particle events (SPE).
• Understanding T cell responses to these distinct radiation types is crucial for astronaut health.

Purpose of the Study:

• To investigate the impact of LDR radiation and simulated SPE (sSPE) proton exposure on T cell function.
• To analyze the combined effects of LDR and sSPE radiation on CD4(+) T cells.

Main Methods:

• C57BL/6 mice were exposed to LDR gamma radiation (0.01 Gy) and/or simulated SPE protons (1.7 Gy).
• CD4(+) T cells were isolated from spleens and analyzed for survival/signaling proteins and cytokines on days 4 and 21 post-exposure.

Main Results:

• LDR priming prior to sSPE exposure significantly altered NF-κB, p38MAPK, and JNK signaling pathways on day 21.
• LDR exposure normalized sSPE-induced changes in Lck levels and affected Zap-70 levels in CD4(+) T cells.
• Cytokine profiles showed increased IL-2 and IL-4, and decreased TGF-β1 in the combined exposure group.

Conclusions:

• Protracted LDR gamma-ray exposure significantly modifies the effects of sSPE protons on CD4(+) T cell signaling and cytokine production.
• This study provides novel insights into the complex immunomodulatory effects of combined space radiation exposures.