Inflammatory response to radiation exposure of immune cells

Background: The purpose of this study was to determine the effect of radiation on the inflammatory signaling response of immune cells. Radiation exposure can increase the risk of developing cardiovascular disease (CVD), which is likely initiated as an inflammatory process. In turn, inflammation initiates atherosclerosis via endothelial cell damage and subsequent immune cell infiltration. We hypothesized that CD14+ immune cells will exhibit an amplified inflammatory response, as demonstrated by larger increases in inflammatory cytokine expression 24 hours post radiation exposure. Methods: Human venous blood was collected from 6 healthy young adults (28 ± 5 years, 22.4 ± 0.7 BMI, 3 Male) using an institutional review board (IRB)-approved protocol. Women were studied in days 1-5 of menstrual cycle. Peripheral blood mononuclear cells (PBMCs) were harvested by density gradient separation. PBMCs were re-suspended and incubated with anti-human CD14 microbeads for 15 minutes at 4°C. After washing unbound antibody, cell separation was done using an autoMACS Pro Separator. CD14+ immune cells were incubated in plates, exposed to 4 gray (Gy) of x-ray radiation, and then incubated for 24 hours. CD14+ immune cells were exposed to 20ng/ml of TNF-α for 30 mins. The culture media was recovered, centrifuged at 100 × g for 1 minute to remove any floating cell debris and assayed for secreted factors, specifically for IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p70, IL-13, INF-γ, and TNF-α. Cytokine responses to radiation were analyzed by paired t-tests. Differences in sex were analyzed by two-way repeated measures ANOVA (Condition x Sex). Results: Radiation exposure (4 Gy) did not change the levels of IL-1β (p=0.15), IL-2 (p=0.13), IL-4 (p=0.16), IL-6 (p=0.18), IL-8 (p=0.35), IL-10 (p=0.18), IL-12p70 (p=0.15), IL-13 (p=0.27), INF-γ (p=0.12), and TNF-α (p=0.14). TNF-α stimulated expression levels of IL-1β (p=0.15), IL-2 (p=0.16), IL-4 (p=0.36), IL-6 (p=0.72), IL-8 (p=0.89), IL-10 (p=0.87), IL-12p70 (p=0.43), IL-13 (p=0.24), and INF-γ (p=0.21) were not different post radiation. There was no sex difference in inflammatory cytokine expression post radiation (p>0.2) or TNF-α stimulation post radiation (p>0.1). Conclusion: These data suggest that expression of inflammatory signals of CD14+ immune cells are not different after exposure to acute radiation (4 Gy x-ray). Further studies are needed to investigate whether increased exposure (duration and/or dose) to radiation could lead to increases in inflammatory cytokines in the adaptive immune response. Translational Research Institute for Space Health through NASA Cooperative Agreement NNX16AO69A and NIH R01 HL150361 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.