Background: Lung is one of the radiosensitive and late responding organs, and is an
important target for ionizing radiation. Radiation-induced pneumonitis and fibrosis are major consequences
of lung exposure to a high dose of radiation and pose threats to the lives of exposed people.
Mitigation of lung injury following an accidental radiation event or for patients with lung cancer
is one of the most interesting issues in radiobiology. In the current study, we aimed to determine
whether celecoxib, the most common cyclooxygenase-2 (COX-2) inhibitor, is able to mitigate
pneumonitis and fibrosis following lung irradiation or not.
Materials and Methods: 20 male mice were assigned to 4 groups: control, celecoxib treatment,
radiation, and radiation plus celecoxib. Irradiation was performed with a dose of 18 Gy cobalt-60
(60Co) gamma rays. Celecoxib treatment (50 mg/kg) started 24 h after irradiation and continued four
times per week for 4 weeks.
Results: Irradiation of lung led to remarkable infiltration of macrophages, lymphocytes, mast cells
and neutrophils. Also, a mild increase in fibrosis markers including accumulation of collagen, and
alveolar and vascular thickening, was observed. Post-exposure treatment with celecoxib was able to
mitigate fibrosis as well as alveolar and vascular changes, however, it was unable to mitigate pneumonitis
Conclusion: Celecoxib showed that it may have an anti-fibrosis effect following exposure of mice
lung to radiation, although it was unable to prevent pneumonitis.