Serum amyloid A1 as a biomarker for radiation dose estimation and lethality prediction in irradiated mouse-reply.

Abstract

Background: Fast and reliable biomarkers are needed to distinguish whether individuals were exposed or not to radiation and assess radiation dose, and to predict the severity of radiation damage in a large-scale radiation accident. Serum amyloid A1 (SAA1) is a protein induced by multiple factors including inflammatory. Therefore, this study aimed at exploring the role of SAA1 in the radiation dose estimation and lethality prediction after radiation. Methods: C57BL/6J female mice were exposed to total body irradiation (TBI) at different doses and time points and amifostine, a drug used to reduce the side effects of radiotherapy, was injected before irradiation. Patients with nasopharyngeal carcinoma subjected to radiotherapy were used as the irradiation model in humans. Results: A moderate SAA1 increase was observed at 6 hours in serum samples from irradiated mice at all doses used, with a peak at 12 hours, then decreased to day 3 after exposure. A second SAA1 increase was observed from day 5 to 7, which was associated to subsequent lethality. Treatment with amifostine before irradiation could prevent mice death and inhibit the second SAA1 increase. SAA1 increase after radiation was confirmed in human serum of nasopharyngeal carcinoma patients after radiotherapy. Conclusions: Serum SAA1 levels could represent a biomarker for radiation dose estimation and its second increase might be a useful lethality indicator after radiation in a mouse model.