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. 2019 Jan 1;8(1):12.
doi: 10.3390/antiox8010012.

Healthcare Workers Occupationally Exposed to Ionizing Radiation Exhibit Altered Levels of Inflammatory Cytokines and Redox Parameters

Iman M Ahmad  1 , Maher Y Abdalla  2 , Tiffany A Moore  3 , Lisa Bartenhagen  4 , Adam J Case  5 , Matthew C Zimmerman  6
Affiliations

Healthcare Workers Occupationally Exposed to Ionizing Radiation Exhibit Altered Levels of Inflammatory Cytokines and Redox Parameters

Iman M Ahmad et al. Antioxidants (Basel). .

Abstract

Studies have shown an increased risk for a variety of cancers, specifically brain cancer, in healthcare workers occupationally exposed to ionizing radiation. Although the mechanisms mediating these phenomena are not fully understood, ionizing radiation-mediated elevated levels of reactive oxygen species (ROS), oxidative DNA damage, and immune modulation are likely involved. A group of 20 radiation exposed workers and 40 sex- and age-matched non-exposed control subjects were recruited for the study. We measured superoxide (O₂•-) levels in whole blood of healthcare workers and all other measurements of cytokines, oxidative DNA damage, extracellular superoxide dismutase (EcSOD) activity and reduced/oxidized glutathione ratio (GSH/GSSG) in plasma. Levels of O₂•- were significantly higher in radiation exposed workers compared to control. Similarly, a significant increase in the levels of interleukin (IL)-6, IL-1α and macrophage inflammatory protein (MIP)-1α in radiation exposed workers compared to control was observed, while there was no significance difference in the other 27 screened cytokines. A significant positive correlation was found between MIP-1α and O₂•- levels with no correlation in either IL-6 or IL-1α. Further, a dose-dependent relationship with significant O₂•- production and immune alterations in radiation exposed workers was demonstrated. There was no statistical difference between the groups in terms of oxidative DNA damage, GSH/GSSG levels, or EcSOD activity. Although the biologic significance of cytokines alterations in radiation exposed workers is unclear, further studies are needed for determining the underlying mechanism of their elevation.

Keywords: DNA oxidation; EcSOD; O2•−; glutathione; inflammatory cytokines; oxidative stress.

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Conflict of interest statement

The authors declare that there is no conflict of interest.

Figures

Figure 1
Figure 1
Summary data showing O2•− levels, reported as electron paramagnetic resonance (EPR) Spectrum Amplitude Intensity, in whole blood of subjects exposed to occupational ionizing radiation (A), and representative EPR spectrum from whole blood samples with (red spectrum) or without (blue spectrum) the 1-hydroxy-3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine (CMH) spin probe (B). The EPR spectrum amplitude is directly proportional to the levels of O2•− in the sample and was quantified as peak-to-peak amplitude intensity as indicated in (B). CR: conventional radiography, IR: interventional radiography, CT: computed tomography. a.u. = arbitrary unit. Data represent the mean ± standard error of the mean (SEM). * p < 0.05 versus control and CR [modified from [7]].
Figure 2
Figure 2
Association between MIP-1α, IL-6 and IL1-1α and O2•− in radiation exposed workers. (A), Correlation analysis of MIP-1α and O2•− (r = 0.6). (B), Correlation analysis of IL-6 and O2•−, (r = 0.2). (C), Correlation analysis of IL-1α and O2•−, (r = −0.22).
Figure 3
Figure 3
Mean values of plasma 8-OHdG concentration (ng/ mL) in all radiation workers compared to control group. Data represent the mean ± SEM, p > 0.05.
Figure 4
Figure 4
Mean values of plasma EcSOD activity (A) and the GSH/GSSG ratio (B) from all radiation workers and control subjects. Data represent the mean ± SEM, p > 0.05.
See this image and copyright information in PMC

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