Serum Lipocalin2 is a potential biomarker of liver irradiation damage

Background/Aim IL-6 IL-1 lipocalin2 (LCN2) liver irradiation oxidative stress TNF-a Lipocalin2 (LCN2) is an acute phase protein. The source of its increased serum level in oxidative stress conditions (ROS) remains still unknown. We prospectively evaluate the serum LCN2 increase after single dose liver irradiation along with hepatic LCN2 gene and protein expression. Methods A single dose of 25 Gray was administered percutaneously to the liver of randomly paired rats after a planning CT scan. Male Wistar rats were sacrificed 1, 3, 6, 12, 24 and 48h after irradiation along with sham-irradiated controls. ELISA, RT-PCR, Western blot and immunofluorescence staining was performed. Furthermore, hepatocytes, myofibroblasts and Kupffer cells were isolated from the liver of healthy rats and irradiated ex-vivo. Results After liver irradiation, LCN2 serum levels increased significantly up to 2.7g/ml within 6h and stayed elevated over 24h. LCN2 specific transcripts increased significantly up to 552 +/- 109-fold at 24h after liver irradiation, which was further confirmed at protein level. 2-macroglobulin and hemoxygenase-1 also showed an increase, but the magnitude was less as compared to LCN2. LCN2+ granulocytes were detected within 1h after irradiation around central and portal fields and remained high during the course of study. Ex-vivo irradiated hepatocytes (2.4 +/- 0.6-fold) showed a higher LCN2 gene expression as compared to myofibroblasts and Kupffer cells. IL-1 treatment further increased LCN2 gene expression in cultured hepatocytes. Conclusions Single dose liver irradiation induces a significant increase in LCN2 serum levels, comparable to the induction of acute phase proteins. We suggest LCN2 as marker for the early phase of radiation-induced tissue damage.