Radiation and pulmonary fibrosis

Radiation-induced pulmonary fibrosis—tissue scarring that can permanently impair lung function—limits the delivery of therapeutic radiation doses to non-small cell lung cancer.

To develop strategies for preventing or reducing fibrosis, Michael Freeman, Ph.D., and colleagues are exploring the cell types and factors that contribute to the radiation-induced fibrotic response.

The investigators previously showed that loss of the transcription factor Nrf2 increases susceptibility to pulmonary fibrosis. They now show that thoracic (chest) radiation of mice causes a loss of alveolar type 2 cells and that this loss is enhanced in mice lacking Nrf2.

The researchers found that a specific stem/progenitor cell population was inhibited following radiation in mice missing Nrf2, and that alveolar type 2 cells in these mice were more likely to change into myofibroblasts—a cell type implicated in fibrosis.

The findings, reported in the November Free Radical Biology and Medicine, demonstrate that Nrf2 participates in stem cell mobilization and helps maintain the alveolar type 2 cell reparative process in injured lungs.