Unilateral Fractionated Thoracic Irradiation Induces Abscopal Injury in Contralateral Lung through NF-κB Pathway

Area of Science:

• Radiation Oncology
• Pulmonary Medicine
• Immunology

Background:

• Radiotherapy can cause damage to non-targeted tissues (abscopal effects).
• The signaling pathways driving abscopal lung injury remain unclear.
• Understanding these mechanisms is crucial for mitigating radiotherapy side effects.

Purpose of the Study:

• To investigate if local thoracic irradiation induces damage in the contralateral, non-irradiated lung.
• To identify the signaling factors involved in radiation-induced abscopal lung injury.
• To evaluate potential therapeutic interventions for mitigating this injury.

Main Methods:

• A murine model received fractionated irradiation to the right lung.
• Scattered radiation effects were excluded as a cause of injury.
• Macrophage activation, specifically NF-κB pathway, was assessed.
• The impact of NF-κB inhibition and cimetidine treatment was evaluated.

Main Results:

• Unilateral thoracic irradiation led to progressive injury in the contralateral lung.
• Increased macrophage activation with NF-κB signaling was observed.
• Inhibition of NF-κB and cimetidine administration significantly reduced pneumonitis and fibrosis.
• Scattered radiation did not account for the observed structural damage or DNA damage.

Conclusions:

• Abscopal lung injury after unilateral irradiation is mediated by activated macrophages.
• The NF-κB pathway plays a key role in radiation-induced pneumonitis and fibrosis.
• Targeting NF-κB or using cimetidine shows therapeutic potential for abscopal lung injury.