Long-term gene expression changes in irradiated male and female rhesus macaque

Purpose: Long-term transcriptome changes can be expected in survivors after lethal irradiation. We aimed to characterize these changes in males and females and after different cytokine treatments. Material and Methods: Peripheral blood was drawn in male and female rhesus macaque (n=142), which survived whole-body exposure with 700 cGy (LD66/60). Peripheral whole blood was drawn pre-exposure and before sacrificing the surviving animals after 60 days. Results: We evaluated gene expression in a three-phase study design where phase I was a whole-genome screening (NGS) for mRNAs using five pre- and post-exposure RNA samples (n=20). Differential gene expression (DGE) was calculated separately for each sex between samples of survivors and pre-exposure samples, utilized as the reference. Altogether 1,243 up- and down-regulated genes were identified. Altogether 37 candidate mRNAs were chosen for validation in phase II using the remaining samples (n=117) and utilizing qRT-PCR. Altogether 17 genes showed significant or borderline significant (t-test) DGE in groups of untreated or treated males and females, but nine most promising genes (CD248, EDAR, FAM19A5, GAL3ST4, GCNT4, HBG2/1, LRRN1, NOG, SYT14). For phase III, we validated our 41 rhesus macaque candidate genes with results from an earlier conducted study on male baboons. Altogether 34% (14 out of 41) genes showed a concordantly DGE in males of both species (DGE defined as (FC) > |1.5|). Conclusions: 60 days after radiation exposure, we identified (1) cytokine treatment independent long-term transcriptional changes, (2) females with almost twice as much deregulated genes appeared more radio-responsive than males on gene expression level but interestingly did not show a correlation between hematopoietic nadirs and sex in corresponding clinical data and (3) Panther analysis revealed a strong association with immunological processes as well as the WNT pathway for both sexes, highlighting a possible correlation of secondary malignancy development due to immunological alterations.