Significant Differences in Thoracic Irradiation-Induced Pulmonary Gene Transcripts Between Fibrosis-Prone C57BL/6NHsd and Fibrosis-Resistant C3H/Hen Mice

Abstract

The initiation mechanism of late radiation fibrosis in some but not all patients remains a mystery. Thoracic irradiation to 20 Gy of C57BL/6NHsd (BLK6) mice produces acute lung inflammation (1 to 30 days after irradiation), a latent period (31 to 125 days), and delayed fibrosis (125 to 200 days). In contrast thoracic irradiation of C3Hf/Kam (C3H) to doses of 14 Gy/16 Gy produces a more severe acute pneumonitis reaction, but no late fibrosis. C3H mice also resist bleomycin, silica, ozone, and hyperoxia induced fibrosis, suggesting a major pathway difference in the late tissue reaction.