Evaluation of the Protective Effect of Compound Kushen Injection Against Radiation- induced Pneumonitis in Mice

Abstract Background Radiation-induced lung injury (RILI) via inflammation is a common adverse effect of thoracic radiation that negatively impacts patient quality of life and survival. Compound kushen injection (CKI), a botanical drug treatment, was examined for its ability to reduce RILI, and inflammatory responses and improve survival in mice exposed total lung irradiation (TLI). CKI’s specific mechanisms of action were also evaluated. Methods C3H mice underwent TLI and were treated with CKI (2, 4, or 8 mL/kg) intraperitoneally once a day for 8 weeks. The effects of CKI on survival were estimated by Kaplan-Meier survival analysis and compared by log-rank test. RILI damage was evaluated by histopathology and micro-computed tomography (CT). Inflammatory cytokines and cyclooxygenase metabolites were examined by IHC staining, western blot, and ELISA. Results Pre-irradiation treatment with 4 or 8 mL/kg CKI starting 2 weeks before TLI or concurrent treatment with 8 mL/kg CKI were associated with a significantly longer survival compared with TLI vehicle-treated group ( P < 0.05). Micro-CT images evaluations showed that concurrent treatment with 8 mL/kg CKI was associated with significantly lower incidence of RILI ( P < 0.05). Histological evaluations revealed that concurrent TLI treatment of CKI (4 and 8 mL/kg) significantly reduced lung inflammation (p < 0.05). Mechanistic investigation showed that at 72 hours after radiation, TLI plus vehicle mice had significantly elevated serum IL6, IL17A, and TGF-β levels compared with non-irradiated, age-matched normal mice; in contrast, levels of these cytokines in mice that received TLI plus CKI treatment were lower than those in the TLI plus vehicle-treated mice ( P < 0.05) and similar to the nonirradiated mice. IHC staining showed that the CKI treatment led to a reduction of TGF-β positive cells in the lung tissues of TLI mice (P < 0.01). The concurrent CKI with TLI treatment group had a significant reduction in COX-2 activity and COX-2 metabolites compared with the TLI vehicle-treated group ( P < 0.05). Conclusions These data suggest that CKI treatment was associated with reduced radiation-induced inflammation in lung tissues, reduced RILI, and improved survival. Further investigation of CKI in human clinical trials as a potential radioprotector against RILI to improve patients’ quality of life and survival is warranted.