Effects of multiple doses of ionizing radiation on cytokine expression in rat and human cells

Abstract

Purpose: To determine the effect of daily fractionated irradiation on the expression of growth factors and cytokines in different cardiac and vascular cell types.

Materials and methods: Cell cultures of rat cardiac myocytes, fibroblasts, a rat cardiac microvascular endothelial cell line and human artery endothelial cells were irradiated with doses of 2 Gy, given daily during 5 consecutive days. Twenty‐four hours after each fraction, gene expression was determined by competitive or semiquantitative polymerase chain reaction. Protein secretion into culture media was determined by enzyme‐linked immunoabsorbant assay.

Results: Of all investigated mRNA levels, transforming growth factor (TGF)‐ß1 and fibroblast growth factor (FGF)‐2 were slightly upregulated in the rat cardiac endothelial cell line after irradiation. TGF‐ß1 protein secretion by these cells was slightly, but non‐significantly, elevated. Interleukin 1ß protein levels in myocyte culture media were decreased in control cultures at days 3 and 4 compared with day 2. No significant changes were observed in expression of FGF‐2 in either of the four cell types. Moreover, no changes were observed in gene expression of platelet‐derived growth factors A, B and interleukin 8 in the human artery endothelial cells.

Conclusions: Fractionated irradiation leads to minor changes in the expression of specific cytokines in cardiac myocytes, fibroblasts and endothelial cells.