P09: Elevated levels of plasma-reactive oxygen species and inflammatory markers among atomic-bomb survivors

Abstract

Even after more than 60 years have passed, exposure to atomic-bomb (A-bomb) radiation continues to have long-term health effects in survivors, whose risks of inflammation-related diseases increase with increasing radiation dose. It is known that persistent inflammation underlies several cancers through increased production of reactive oxygen species (ROS) and endogenous tumor promoters (e.g., TNF-α). In our previous study, plasma levels of inflammatory cytokines and biomarkers, IL-6, TNF-α, CRP, IFN-γ, Igs, and erythrocyte sedimentation rate (ESR), increased significantly with radiation dose. We have recently developed an automated plasma ROS assay system based on use of a clinical chemistry analyzer. In this study we investigated association between radiation dose, plasma ROS levels, and sub-clinical inflammatory status in A-bomb survivors in Hiroshima. Excluding patients with history of cancer, rheumatoid arthritis, chronic bronchitis, or myocardial infarction, we randomly selected 442 study subjects from the Adult Health Study population, consisting of A-bomb survivors and unexposed people. We observed statistically significant radiation-associated increase in plasma ROS levels. ROS levels were positively associated with the inflammatory biomarkers IL-6, TNF-α, CRP, and ESR ( P It is evident that total ROS production increased with enhanced inflammatory status, suggesting a plausible mechanistic pathway between radiation-induced persistent inflammation and cancer.