Serum Metabolomic Signatures in Nonhuman Primates Treated with a Countermeasure and Exposed to Partial- or Total-Body Radiation

Background: Irradiation-induced injury is a common fallout of radiological/nuclear accidents or therapeutic exposures to high doses of radiation at high dose rates. Currently, there are no prophylactic drugs available to mitigate radiation injury as a result of exposure to lethal doses of ionizing radiation. Gamma-tocotrienol (GT3) of vitamin E is a promising radioprotector under advanced development which has been tested for efficacy in both murine and nonhuman primate (NHP) models. Previously, we have demonstrated that GT3 has radioprotective efficacy in intestinal epithelial and crypt cells, and restores transcriptomic changes in NHPs with a supralethal dose of 12 Gy total-body irradiation (TBI). Methods: In this study, we evaluated the effect of 12 Gy partial-body irradiation (PBI) or TBI on metabolomic changes in serum samples and the extent to which GT3 was able to modulate these irradiation-induced changes. A total of 32 nonhuman primates were used for this study, and blood sample were collected 3 days (d) prior to irradiation, and 4 h, 8 h, 12 h, 1 d, 2 d, and 6 d post-irradiation. Results: Our results demonstrate that exposure to a supralethal dose of radiation induces a complex range of metabolomic shifts with similar degrees of dysregulation in both partial- and total-body irradiated animals. The C21-steroid hormone biosynthesis and metabolism pathway was significantly dysregulated in both PBI and TBI groups, with minimal protection afforded by GT3 administration. Conclusions: GT3 offered a differential response in terms of protected metabolites and pathways in either group that was most effective at the early post-irradiation time points.