Title:Lung Pneumonitis and Fibrosis in Cancer Therapy: A Review on Cellular
and Molecular Mechanisms
Volume: 23
Issue: 16
Author(s): Chaofeng Xu*, Zhongtu Shang and Masoud Najafi*
Affiliation:
- Zhuji People's Hospital of Zhejiang Province, Zhuji Affiliated Hospital of Shaoxing University, Zhuji, Zhejiang, 311800, China
- Medical Technology Research Center, Kermanshah University of Medical Sciences, Kermanshah, Iran
- Radiology and Nuclear Medicine Department, School of Paramedical Sciences, Kermanshah University of Medical Sciences, Kermanshah, Iran
Keywords:
Chemotherapy, radiotherapy, lung, fibrosis, pneumonitis, EMT.
Abstract: Fibrosis and pneumonitis are the most important side effects of lung tissue following
cancer therapy. Radiotherapy and chemotherapy by some drugs, such as bleomycin, can induce
pneumonitis and fibrosis. Targeted therapy and immunotherapy also may induce pneumonitis and
fibrosis to a lesser extent compared to chemotherapy and radiotherapy. Activation of lymphocytes
by immunotherapy or infiltration of inflammatory cells such as macrophages, lymphocytes, neutrophils,
and mast cells following chemo/radiation therapy can induce pneumonitis. Furthermore, the
polarization of macrophages toward M2 cells and the release of anti-inflammatory cytokines stimulate
fibrosis. Lung fibrosis and pneumonitis may also be potentiated by some other changes such as
epithelial-mesenchymal transition (EMT), oxidative stress, reduction/oxidation (redox) responses,
renin-angiotensin system, and the upregulation of some inflammatory mediators such as a nuclear
factor of kappa B (NF-κB), inflammasome, cyclooxygenase-2 (COX-2), and inducible nitric oxide
synthase (iNOS). Damages to the lung vascular system and the induction of hypoxia also can induce
pulmonary injury following chemo/radiation therapy. This review explains various mechanisms of
the induction of pneumonitis and lung fibrosis following cancer therapy. Furthermore, the targets
and promising agents to mitigate lung fibrosis and pneumonitis will be discussed.