Temporal Effects on Radiation Responses in Nonhuman Primates: Identification of Biofluid Small Molecule Signatures by Gas Chromatography⁻Mass Spectrometry Metabolomics.

Evan Pannkuk,Sarah Dowd,Michael Girgis,Suraj Dhungana,Denise Nishita,Janet Gahagen,Polly Chang,Simon Authier,Albert Fornace, Jr,Evagelia Laiakis,James Bakke,Kim Bujold

doi:10.3390/metabo9050098

Abstract

Whole body exposure to ionizing radiation damages tissues leading to physical symptoms which contribute to acute radiation syndrome. Radiation biodosimetry aims to determine characteristic early biomarkers indicative of radiation exposure and is necessary for effective triage after an unanticipated radiological incident. Radiation metabolomics can address this aim by assessing metabolic perturbations following exposure. Gas chromatography–mass spectrometry (GC-MS) is a standardized platform ideal for compound identification. We performed GC time-of-flight MS for the global profiling of nonhuman primate urine and serum samples up to 60 d after a single 4 Gy γ-ray total body exposure. Multivariate statistical analysis showed higher group separation in urine vs. serum. We identified biofluid markers involved in amino acid, lipid, purine, and serotonin metabolism, some of which may indicate host microbiome dysbiosis. Sex differences were observed for amino acid fold changes in serum samples. Additionally, we explored mitochondrial dysfunction by tricarboxylic acid intermediate analysis in the first week with a GC tandem quadrupole MS platform. By adding this temporal component to our previous work exploring dose effects at 7 d, we observed the highest fold changes occurring at 3 d, returning closer to basal levels by 7 d. These results emphasize the utility of both MS-based metabolomics for biodosimetry and complementary analytical platforms for increased metabolome coverage.

Highlights

Exposure to external ionizing radiation (IR) can include occupational hazards [1] or accidents from nuclear energy [2] to normal backgroundMetabolites 2019, 9, 98; doi:10.3390/metabo9050098 www.mdpi.com/journal/metabolitesMetabolites 2019, 9, 98 radiation [3]
The majority of studies defining biophysiological responses to radiation exposures have focused on LC-mass spectrometry (MS) platforms [7], these methods lack in chromatographic separation of small volatile compounds or isomers and availability of well-established RI and mass spectral libraries available in the realm of Gas chromatography–mass spectrometry (GC-MS) analyses
~5–10 min) and sample preparation for required derivatization (~60 min vs. ~5 min) limits its direct use in biodosimetry for time-sensitive emergency situations, GC-MS serves as a complementary platform to LC-MS providing more depth into metabolite coverage, such as the tricarboxylic acid (TCA) cycle intermediates described in this study

Summary

Introduction

Exposure to external ionizing radiation (IR) can include occupational hazards [1] or accidents from nuclear energy (e.g., deposition of 137 Cs after the Chernobyl accident) [2] to normal backgroundMetabolites 2019, 9, 98; doi:10.3390/metabo9050098 www.mdpi.com/journal/metabolitesMetabolites 2019, 9, 98 radiation [3]. The potential of malicious use of radioactive materials, such as a radiological dispersal device (RDD) or improvised nuclear device (IND), for terrorist actions has been of concern. There is a need for predictive biomarkers indicative of radiation exposure to aid in the triage of large populations during a potential radiological terrorism act. Countermeasures against Radiation Consortium (CMCRC) program [6]. Of these needs, our group has a particular interest in the use of mass spectrometry (MS) platforms for radiation biomarker development, aiding in rapid high-throughput biodosimetry and the assessment of acute radiation syndrome (ARS), and associated tissue damage and recovery [7]

Methods

Results

Conclusion