Abstract
Background
Radiation exposure is known to increase the risk of chronic inflammatory diseases, such as atherosclerosis, by modulating inflammation.
Methods
To investigate the infiltration of leukocytes in radiation-aggravated atherosclerosis, we examined low-density lipoprotein receptor-deficient (Ldlr–/–) mice and C57BL/6j mice after exposure to 0.5 or 1 Gy radiation over 16 weeks.
Results
We found that radiation exposure induced atherosclerosis development in Ldlr–/– mice, as demonstrated by increased lipid-laden plaque size, reactive oxygen species levels, and levels of the pro-inflammatory cytokines, IL-1β and TNF-α, in the aortas and spleens. Total plasma cholesterol, triglyceride, and LDL cholesterol levels were also increased by radiation exposure, along with cardiovascular risk. We also showed dose-dependent increases in neutrophils and monocytes that coincided with a reduction in lymphocytes in the spleens of Ldlr–/– mice. The correlation between the infiltration of leukocytes and cytokine production was also confirmed in the hearts and spleens of these mice.
Conclusions
We concluded that chronic radiation exposure increased the production of pro-inflammatory mediators, which was associated with the migration of neutrophils and inflammatory monocytes into sites of atherosclerosis. Thus, our data suggest that the accumulation of neutrophils and inflammatory monocytes, together with the reduction of lymphocytes, contribute to aggravated atherosclerosis in Ldlr–/– mice under prolonged exposure to radiation.
Disclosure statement
The authors declare no conflict of interest.
Additional information
Funding
Notes on contributors
You Yeon Choi
You Yeon Choi is a Post-Doctor in National Radiation Emergency Medical Center. She is currently studying the radiation effects on atherosclerosis at low doses using a model mouse and cytogenetic and biochemical methods to examine the exposed level to radiation from human blood.
Areumnuri Kim
Areumnuri Kim is a Senior Researcher in National Radiation Emergency Medical Center. She has investigated to explain hematological response of ionizing radiation after radiotherapy and explored the immunological response in the radiation-induced intestinal damage.
Ki Moon Seong
Ki Moon Seong is a Senior Researcher in National Radiation Emergency Medical Center. His research interest is the biological effects of radiation exposure at low doses in daily life and biodosimetry on the people exposed to radiation. Currently, he contributes to the collaborating works of UNSCEAR as a Korean delegate.